Echange coupling film and magnetoresistive element using the same

ABSTRACT

An exchange coupling film including an antiferromagnetic layer and a ferromagnetic layer in contact with the antiferromagnetic layer so as to generate an exchange coupling magnetic field is provided. A PtMn alloy is used as the material of the antiferromagnetic layer. Crystal planes of the antiferromagnetic layer and the ferromagnetic layer preferentially aligned parallel to the interface are crystallographically identical and crystallographically identical axes lying in these crystal planes are oriented, at least partly, in different directions between the antiferromagnetic layer and the ferromagnetic layer. Thus, a proper order transformation occurs in the antiferromagnetic layer as a result of heat treatment and an increased exchange coupling magnetic field can be obtained.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an exchange coupling filmcomprising an antiferromagnetic layer and a ferromagnetic layer, inwhich the magnetization vector of the ferromagnetic layer is oriented ina particular direction by an exchange coupling magnetic field generatedat the interface between the antiferromagnetic layer and theferromagnetic layer. The present invention is particularly directed toan exchange coupling film having a strong exchange coupling magneticfield, a magnetoresistive element (spin valve thin-film element or AMRelement) employing the exchange coupling film, and a thin-film magnetichead incorporating the magnetoresistive element.

[0003] 2. Description of the Related Art

[0004] A spin-valve thin-film magnetic head is a type of giantmagnetoresistive element (GMR) which utilizes the giant magnetoresistiveeffect. The spin-valve thin-film magnetic head detects a recordedmagnetic field from a recording medium such as a hard disk.

[0005] The spin-valve thin-film magnetic head is preferred for itsrelatively simple structure compared to other GMR elements and itsability to change the resistance in response to a weak magnetic field.

[0006] The simplest type of spin-valve thin-film magnetic head comprisesan antiferromagnetic layer, a pinned magnetic layer, a nonmagneticinterlayer, and a free magnetic layer.

[0007] The antiferromagnetic layer and the pinned magnetic layer are incontact with each other. An exchange anisotropic magnetic fieldgenerated at the interface between the antiferromagnetic layer and thepinned magnetic layer puts the magnetization vector of the pinnedmagnetic layer into a single domain state, thus pinning themagnetization vector.

[0008] The magnetization vector of the free magnetic layer is orientedin a direction substantially orthogonal to the magnetization vector ofthe pinned magnetic layer by bias layers formed on two sides of the freemagnetic layer.

[0009] The antiferromagnetic layer is typically composed of an Fe—Mnalloy, a Ni—Mn alloy, or a Pt—Mn alloy. The Pt—Mn alloy is particularlypreferable since this alloy has a high blocking temperature, excellentcorrosion resistance, and other advantageous features.

[0010] The inventors have found that even when the PtMn alloy is used inthe antiferromagnetic layer, there are some instances where an exchangecoupling magnetic field generated between the antiferromagnetic layerand the pinned magnetic layer has a reduced intensity.

[0011] When the antiferromagnetic layer is composed of the PtMn alloy,the disordered lattice of the antiferromagnetic layer can be transformedinto an ordered lattice by thermally treating the antiferromagneticlayer and the pinned magnetic layer subsequent to their deposition, soas to generated an exchange coupling magnetic field.

[0012] However, when the atoms of the antiferromagnetic materialconstituting the antiferromagnetic layer and the atoms of the softmagnetic material constituting the pinned magnetic layer exhibit aone-to-one correspondence (lattice matching) at the interface betweenthe antiferromagnetic layer and the pinned magnetic layer, thetransformation into an ordered lattice does not occur properly in theantiferromagnetic layer. As a result, it becomes impossible to obtain anincreased exchange coupling magnetic field.

[0013] The above-described lattice matching is considered to occur whenthe crystal orientations of the antiferromagnetic layer and the pinnedmagnetic layer are coincident with each other at the interface thereof.An example of such an instance is when the one of the {111} planes ofthe antiferromagnetic layer is preferentially aligned parallel to theinterface with the pinned magnetic layer at the same time one of the{111} planes of the pinned magnetic layer is preferentially aligned in adirection parallel to the above-described interface.

SUMMARY OF THE INVENTION

[0014] Accordingly, it is an object of the present invention to providean exchange coupling film overcoming the above-described drawbacks ofthe conventional art. The exchange coupling film of the presentinvention generates an increased exchange anisotropic magnetic fieldwhen an antiferromagnetic material containing X (X is a platinum groupelement) and Mn is used in an antiferromagnetic layer. Amagnetoresistive element using the exchange coupling film and thethin-film magnetic head incorporating the magnetoresistive element arealso provided.

[0015] To achieve the above-described object, an exchange coupling filmaccording to an aspect of the present invention has an antiferromagneticlayer and a ferromagnetic layer in contact with the antiferromagneticlayer. An exchange coupling magnetic field generated at the interfacebetween the antiferromagnetic layer and the ferromagnetic layermagnetizes the antiferromagnetic layer in a particular direction. Theantiferromagnetic layer includes an antiferromagnetic materialcontaining Mn and X′, wherein X is at least one element selected fromthe group consisting of Pt, Pd, Ir, Rh, Ru, and Os. Crystal planes ofthe antiferromagnetic layer and the ferromagnetic layer, preferentiallyaligned parallel to the interface, are crystallographically identical,and crystallographically identical axes lying in said crystal planes areoriented, at least partly, in different directions between theantiferromagnetic layer and the ferromagnetic layer.

[0016] The above-described crystal planes are preferably thecrystallographically identical planes generically described as the {111}planes. The crystallographically identical axes are preferably the axesgenerically described as the <110> axes.

[0017] According to the present invention, a proper order transformationoccurs in the antiferromagnetic layer through heat treatment, and anincreased exchange coupling magnetic field can be generated, even whenthe crystal planes of the antiferromagnetic layer and the ferromagneticlayer preferentially aligned parallel to the layer surface arecrystallographically identical.

[0018] In the present invention, the crystallographically identical axeslying in the above-described crystal planes are oriented, at leastpartly, in different directions between the antiferromagnetic layer andthe ferromagnetic layer.

[0019] In the present invention, the crystal planes in theantiferromagnetic layer and the ferromagnetic layer, preferentiallyaligned parallel to the layer surface are crystallographicallyidentical, and the crystallographically identical axes lying in thesecrystal planes are oriented, at least partly, in different directionsbetween the antiferromagnetic layer and the ferromagnetic layer. Thesecrystal orientations can be identified from transmission electron beamdiffraction diagrams.

[0020] Another aspect of the present invention provides an exchangecoupling film having an antiferromagnetic layer and a ferromagneticlayer in contact with the antiferromagnetic layer, an exchange couplingmagnetic field generated at the interface between the antiferromagneticlayer and the ferromagnetic layer magnetizing the ferromagnetic layer ina particular direction. Diffraction spots corresponding to reciprocallattice points indicative of crystal planes of the antiferromagneticlayer and the ferromagnetic layer appear in transmission electron beamdiffraction diagrams of the antiferromagnetic layer and theferromagnetic layer, which are obtained by using an electron beam in adirection parallel to the interface. The first imaginary lines in thediffraction diagrams of the antiferromagnetic layer and theferromagnetic layer are coincident with each other, the first imaginarylines each connecting a beam origin and a particular one of thediffraction spots, which is given the same label in both the diffractiondiagrams of the antiferromagnetic layer and the ferromagnetic layer, andwhich is located in a layer thickness direction when viewed from thebeam origin. The second imaginary line in the diffraction diagrams ofthe antiferromagnetic layer and the ferromagnetic layer are notcoincident with each other, the second imaginary lines each connectingthe beam origin and a particular one of the diffraction spots, which isgiven the same label in both the diffraction diagrams of theantiferromagnetic layer and the ferromagnetic layer, and which islocated in a direction other than the layer thickness direction whenviewed from the beam origin.

[0021] The present invention also provides an exchange coupling filmincluding an antiferromagnetic layer and a ferromagnetic layer incontact with the antiferromagnetic layer, in which an exchange couplingmagnetic field generated at the interface between the antiferromagneticlayer and the ferromagnetic layer orients the magnetization vector ofthe ferromagnetic layer in a particular direction, and in whichdiffraction spots corresponding to reciprocal lattice points indicativeof crystal planes of the antiferromagnetic layer and the ferromagneticlayer appear in transmission electron beam diffraction diagrams of theantiferromagnetic layer and the ferromagnetic layer obtained using anelectron beam in a direction parallel to the interface. The firstimaginary lines in the diffraction diagrams of the antiferromagneticlayer and the ferromagnetic layer are coincident with each other, thefirst imaginary lines each connecting a beam origin and a particular oneof the diffraction spots, which is given the same label in both thediffraction diagrams of the antiferromagnetic layer and theferromagnetic layer, and is located in a layer thickness direction whenviewed from the beam origin. A particular diffraction spot indicative ofa particular crystal plane, located in a direction other than the layerthickness direction, appears only in one of the diffraction diagrams ofthe antiferromagnetic layer and the ferromagnetic layer.

[0022] Preferably, the diffraction spots located in the layer thicknessdirection are assigned to the {111} planes.

[0023] In this embodiment, the crystal orientations of theantiferromagnetic layer and the ferromagnetic layer are determined bytransmission electron beam diffraction diagrams obtained using anelectron beam entering in a direction parallel to the interface.

[0024] Herein, the transmission electron beam diffraction diagrams referto the diagrams obtained using a transmission electron beam microscopeor the like. The diffraction diagrams present diffraction phenomenabrought about by the scattering of the electron beam (Bragg reflection)when the electron beam is entered and transmitted through the testsubjects.

[0025] The diffraction spots appearing in the above diffraction diagramsare labeled based on the labeled diffraction patterns of typical singlecrystal structures.

[0026] The crystal orientations of the antiferromagnetic layer and theferromagnetic layer can be examined through the diffraction diagrams.

[0027] The present invention further provides an exchange coupling filmhaving an antiferromagnetic layer and a ferromagnetic layer in contactwith the antiferromagnetic layer in which an exchange coupling magneticfield generated at the interface between the antiferromagnetic layer andthe ferromagnetic layer magnetizing the ferromagnetic layer in aparticular direction. Diffraction spots corresponding to reciprocallattice points indicative of crystal planes of the antiferromagneticlayer and the ferromagnetic layer appear in transmission electron beamdiffraction diagrams of the antiferromagnetic layer and theferromagnetic layer obtained using an electron beam in a directionperpendicular to the interface. An imaginary line in the diffractiondiagram of the antiferromagnetic layer connecting a beam origin and adiffraction spot given a particular label and an imaginary line in thediffraction diagram of the ferromagnetic layer connecting the beamorigin and a diffraction spot given the same label are not coincidentwith each other.

[0028] Alternatively, among the above-described diffraction spots, adiffraction spot given a particular label may appear only in one of thediffraction diagrams of the antiferromagnetic layer and theferromagnetic layer.

[0029] Preferably, the direction perpendicular to the above-describedinterface is the direction of the crystallographically identical crystalaxes generically described as the <111> axes.

[0030] In this embodiment, the antiferromagnetic layer and theferromagnetic layer preferably has one of the crystallographicallyidentical planes, generically described as the {111} planes,preferentially aligned parallel to the interface of theantiferromagnetic layer and the ferromagnetic layer, and thetransmission electron beam diffraction diagrams are obtained using anelectron beam perpendicular to the interface.

[0031] In order to achieve the above-described crystal orientation, aseed layer may be provided in the exchange-coupling film of the presentinvention.

[0032] Preferably, the exchange coupling film according to the presentinvention further has a seed layer provided below the antiferromagneticlayer. The seed layer mainly has a face-centered cubic structure and hasa crystal plane crystallographically identical to the (111) planepreferentially aligned parallel to the interface.

[0033] By providing a seed layer below the antiferromagnetic layer, oneof the crystallographically identical planes generically described asthe {111} planes can be preferentially aligned parallel to the layersurface in each of the antiferromagnetic layer and the ferromagneticlayer. When the crystallographically identical planes are alignedparallel to the layer surface, an increased rate of change in resistance(ΔR/R) compared to the conventional technology can be obtained.

[0034] Preferably, the seed layer includes one of a NiFe alloy and aNi—Fe—Y alloy, wherein Y is at least one element selected from the groupconsisting of Cr, Rh, Ta, Hf, Nb, Zr, and Ti. The seed layer ispreferably nonmagnetic at room temperature.

[0035] Preferably, an underlayer is provided under the seed layer. Theunderlayer preferably contains at least one element selected from thegroup consisting of Ta, Hf, Nb, Zr, Ti, Mo, and W.

[0036] Preferably, at least part of the interface between theantiferromagnetic layer and the seed layer is in a lattice-mismatchingstate.

[0037] In this invention, the antiferromagnetic material preferablyfurther contains X′, wherein X′ is at least one element selected fromthe group consisting of Ne, Ar, Kr, Xe, Be, B, C, N, Mg, Al, Si, P, Ti,V, Cr, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, Cd, Sn, Hf, Ta, W,Re, Au, Pb, and rare earth elements. Preferably, the antiferromagneticmaterial is an interstitial solid solution in which this X′ is insertedto interstices in the lattice formed by X and Mn, or a substitutionalsolid solution in which this X′ partly displaces the lattice points inthe crystal lattice formed by X and Mn. In this manner, the latticeconstant of the antiferromagnetic layer can be increased, and it becomespossible to prevent a one-to-one correspondence in the atomicarrangements between the antiferromagnetic layer and the ferromagneticlayer.

[0038] In order to make the exchange coupling film having theabove-described crystal orientations, the ratio of each componentconstituting the antiferromagnetic layer is important.

[0039] In order to obtain an increased exchange coupling magnetic field,at least part of the interface between the antiferromagnetic layer andthe ferromagnetic layer needs to be in a lattice-mismatching state, anda proper order transformation needs to be achieved in theantiferromagnetic layer as a result of heat treatment. Whether or notsuch lattice-mismatching state and the proper order transformation areachieved mainly depends on the composition of the antiferromagneticlayer.

[0040] In the present invention, the X or X+X′ content in theantiferromagnetic material is preferably in the range of 45 to 60 atomicpercent. In this manner, an exchange coupling magnetic field of 1.58×10⁴(A/m) or more can be obtained. More preferably the X or X+X′ content inthe antiferromagnetic material is in the range of 49 to 56.5 atomicpercent. In this manner, an exchange coupling magnetic field of 7.9×10⁴(A/m) or more can be obtained.

[0041] By setting the ratio of the components in the above-describedranges, the interface between the antiferromagnetic layer and theferromagnetic layer can keep the lattice-mismatching state and a properorder transformation can be developed in the antiferromagnetic layer asa result of heat treatment.

[0042] After the heat treatment, the crystal planes of theantiferromagnetic layer and the ferromagnetic layer preferentiallyaligned parallel to the layer surface are crystallographicallyidentical. Moreover, the crystal axes lying in these crystal planes areoriented, at least partly, in different directions between theantiferromagnetic layer and the ferromagnetic layer.

[0043] In this invention, at least part of the interface between theantiferromagnetic layer and the ferromagnetic layer is in alattice-mismatching state after the heat treatment.

[0044] The exchange coupling film of the present invention can beapplied to various types of magnetoresistive elements.

[0045] A magnetoresistive element incorporating the exchange couplingfilm of the present invention has the exchange coupling film of thepresent invention, a free magnetic layer formed on the pinned magneticlayer separated by a nonmagnetic interlayer, and bias layers formagnetizing the free magnetic layer in a direction substantiallyorthogonal to the magnetization vector of the pinned magnetic layer.

[0046] The present invention also provides a magnetoresistive elementhaving an antiferromagnetic layer, a pinned magnetic layer in contactwith the antiferromagnetic layer, the magnetization vectors of thepinned magnetic layer being pinned by an exchange anisotropic magneticfield generated in relation to the antiferromagnetic layer, a freemagnetic layer formed on the pinned magnetic layer separated by anonmagnetic interlayer, and antiferromagnetic exchange bias layersformed above or below the free magnetic layer, the exchange bias layersbeing separated from one another in a track width direction by a gaptherebetween. The exchange bias layers and the free magnetic layer arecomposed of the exchange coupling film of the present invention, theexchange bias layers corresponding to the antiferromagnetic layer andthe free magnetic layer corresponding to the ferromagnetic layer, so asto magnetize the free magnetic layer in a particular direction.

[0047] The present invention also provides a magnetoresistive elementincluding nonmagnetic interlayers provided above and below a freemagnetic layer, pinned magnetic layers, one thereof being provided onthe pinned magnetic layer formed on the free magnetic layer and theother being provided under the pinned magnetic layer formed under thefree magnetic layer, antiferromagnetic layers for pinning themagnetization vectors of the pinned magnetic layers, one of theantiferromagnetic layers being provided on one of the pinned magneticlayers and the other being provided under the other of the pinnedmagnetic layers, and bias layers for orienting the magnetization vectorof the free magnetic layer in a direction substantially orthogonal tothe magnetization vector of the pinned magnetic layer. Eachantiferromagnetic layer and the pinned magnetic layer in contact withthe antiferromagnetic layer is constituted from an exchange couplingfilm of the present invention, the pinned magnetic layer correspondingto the ferromagnetic layer.

[0048] The present invention further provides a magnetoresistive elementhaving a magnetoresistive layer, a soft magnetic layer provided on themagnetoresistive layer separated by a nonmagnetic layer therebetween,and antiferromagnetic layers provided above or below themagnetoresistive layer, the antiferromagnetic layers being separatedfrom one another in a track width direction with a gap therebetween. Theantiferromagnetic layers and the magnetoresistive layer are constitutedfrom the exchange coupling film of the present invention, themagnetoresistive layer corresponding to the ferromagnetic layer.

[0049] The present invention also provides a thin-film magnetic head inwhich shield layers are formed above and below the above-describedmagnetoresistive element with gap layers therebetween.

BRIEF DESCRIPTION OF THE DRAWINGS

[0050]FIG. 1 is a cross-section illustrating the structure of a singlespin-valve magnetoresistive element according to a first embodiment ofthe present invention as viewed from an air bearing surface side;

[0051]FIG. 2 is a cross-section illustrating the structure of a singlespin-valve magnetoresistive element according to a second embodiment ofthe present invention as viewed from an air bearing surface side;

[0052]FIG. 3 is a cross-section illustrating the structure of a singlespin-valve magnetoresistive element according to a third embodiment ofthe present invention as viewed from an air bearing surface side;

[0053]FIG. 4 is a cross-section illustrating the structure of a singlespin-valve magnetoresistive element according to a fourth embodiment ofthe present invention as viewed from an air bearing surface side;

[0054]FIG. 5 is a cross-section illustrating the structure of a dualspin-valve magnetoresistive element according to a fifth embodiment ofthe present invention as viewed from an air bearing surface side;

[0055]FIG. 6 is a cross-section illustrating the structure of a AMRmagnetoresistive element according to a sixth embodiment of the presentinvention as viewed from an air bearing surface side;

[0056]FIG. 7 is a cross-section illustrating the structure of a AMRmagnetoresistive element according to a second embodiment of the presentinvention as viewed from an air bearing surface side;

[0057]FIG. 8 illustrates the magnetoresistive element shown in FIG. 1 inits as-deposited state;

[0058]FIG. 9 illustrates the structures of the layers after a heattreatment of the magnetoresistive element shown in FIG. 8;

[0059]FIG. 10 illustrates the magnetoresistive element shown in FIG. 5in its as-deposited state;

[0060]FIG. 11 illustrates the structures of the layers after a heattreatment of the magnetoresistive element shown in FIG. 10;

[0061]FIG. 12 is a cross-sectional view showing the structure of athin-film magnetic head (read head) according to the present invention;

[0062]FIG. 13 is a graph showing the relationship between the Pt contentin an antiferromagnetic layer (PtMn alloy layer) and an exchangecoupling magnetic field (Hex);

[0063]FIG. 14 illustrates the crystal orientation of theantiferromagnetic layer and the crystal orientation of the ferromagneticlayer in the exchange coupling film of the present invention;

[0064]FIG. 15 illustrates the crystal orientation of theantiferromagnetic layer and the crystal orientation of the ferromagneticlayer in the exchange coupling film for comparison;

[0065]FIG. 16 is a transmission electron beam diffraction diagram in adirection parallel to the layer surface of a spin valve film of thepresent invention;

[0066]FIG. 17 is a transmission electron beam diffraction diagram in adirection parallel to the layer surface of a spin valve film forcomparison;

[0067]FIG. 18 illustrates a portion of the transmission electron beamdiffraction diagram in FIG. 16;

[0068]FIG. 19 illustrates a portion of the transmission electron beamdiffraction diagram in FIG. 17;

[0069]FIG. 20 is an illustration of a transmission electron beamdiffraction diagram of the antiferromagnetic layer according to thepresent invention using an electron beam perpendicular to the layersurface;

[0070]FIG. 21 is an illustration of a transmission electron beamdiffraction diagram of the ferromagnetic layer according to the presentinvention using an electron beam perpendicular to the layer surface;

[0071]FIG. 22 is an illustration in which the transmission electron beamdiffraction diagrams shown in FIGS. 20 and 21 are superimposed on eachother;

[0072]FIG. 23 is an illustration of a transmission electron beamdiffraction diagram of the antiferromagnetic layer for comparison usingan electron beam perpendicular to the layer surface;

[0073]FIG. 24 is an illustration of a transmission electron beamdiffraction diagram of the ferromagnetic layer for comparison using anelectron beam perpendicular to the layer surface;

[0074]FIG. 25 is an illustration in which the transmission electron beamdiffraction diagrams shown in FIGS. 23 and 24 are superimposed on eachother;

[0075]FIG. 26 is a transmission electron beam micrograph of across-section of the spin-valve thin-film element of the presentinvention parallel to the layer thickness direction;

[0076]FIG. 27 is a transmission electron beam micrograph of a crosssection of the spin-valve thin-film element for comparison parallel tothe layer thickness direction;

[0077]FIG. 28 is an illustration of a portion of the transmissionelectron beam micrograph shown in FIG. 26; and

[0078]FIG. 29 is an illustration of a portion of the transmissionelectron beam micrograph shown in FIG. 27.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0079]FIG. 1 is a cross-sectional view of a structure of a singlespin-valve magnetoresistive element according to a first embodiment ofthe present invention as viewed from the air bearing surface side. Onlythe central portion of the element extending in the X direction is cutand is shown in FIG. 1.

[0080] The single spin-valve thin-film magnetic element is typicallydisposed at the trailing end face of a floating slider provided in ahard disk device and detects the recorded magnetic field of a hard diskor the like. A magnetic recording medium, typically a hard disk, movesin the Z direction, and the direction of a leakage magnetic field fromthe magnetic recording medium is in the Y direction.

[0081] The bottom-most layer in FIG. 1 is an underlayer 6 composed of anonmagnetic material including at least one element selected from thegroup consisting of Ta, Hf, Nb, Zr, Ti, Mo, and W. A seed layer 22 isprovided on the underlayer 6. The underlayer 6 is provided topreferentially align one of the crystallographically identical planesgenerically described as {111} planes of the seed layer 22 in adirection parallel to the layer surface. The underlayer 6 has athickness of, for example, approximately 50 angstroms.

[0082] In the seed layer 22 which is mainly composed of face centeredcubic crystals, one of the crystallographically identical crystal planesgenerically described as the {111} planes are preferentially alignedparallel to the interface with the antiferromagnetic layer 4. The seedlayer 22 preferably comprises a NiFe alloy or a Ni—Fe—Y alloy wherein Yis at least one element selected from the group consisting of Cr, Rh,Ta, Hf, Nb, Zr, and Ti.

[0083] Herein, “crystallographically identical planes” refers to certaincrystal lattice planes described in terms of Miller indices. Thecrystallographically identical planes described as the {111} planesinclude the (111) plane, the (−111) plane, the (1−11) plane, the (11−1)plane, the (−111) plane, the (1−1−1) plane, the (−11−1) plane, and the(1−1−1) plane.

[0084] In the first embodiment, the (111) plane, the (1−11) plane, orone of the other crystallographically identical planes is preferentiallyaligned parallel to the layer surface.

[0085] Preferably, the seed layer 22 is nonmagnetic at room temperature.When the seed layer 22 is nonmagnetic at room temperature, degradationin asymmetry of waveforms can be prevented, the specific resistance ofthe seed layer 22 can be increased as a result of adding element Y(described later) for making the seed layer nonmagnetic, and it becomespossible to inhibit a sense current supplied from a conductive layer toflow into the seed layer 22. When the sense current easily flows intothe seed layer 22, the rate of change in specific resistance (ΔR/R) isreduced and Barkhausen noise is generated.

[0086] In order to form the nonmagnetic seed layer 22, theabove-described Ni—Fe—Y alloy, wherein Y is at least one selected fromthe group consisting of Cr, Rh, Ta, Hf, Nb, Zr, and Ti, may be selected.This material is preferable because the material has a face-centeredcubic structure and one of the crystallographically identical planesdescribed as the {111} planes can easily be preferentially alignedparallel to the layer surface. The seed layer 22 has a thickness of, forexample, approximately 30 angstroms.

[0087] An antiferromagnetic layer 4 is formed on the seed layer 22. Theantiferromagnetic layer 4 preferably includes an antiferromagneticmaterial containing manganese (Mn) and element X wherein X is at leastone element selected from the group consisting of Pt, Pd, Ir, Rh, Ru,and Os.

[0088] The X—Mn alloy containing at least one platinum group element hasa number of excellent characteristics as an antiferromagnetic material,such as superior corrosion resistance and a high blocking temperature.The alloy is also capable of generating a strong exchange couplingmagnetic field (Hex). It is especially preferable to use platinum (Pt)among the platinum group elements. A binary alloy, for example, a PtMnalloy, may be used.

[0089] Alternatively, the antiferromagnetic layer 4 may be made of anantiferromagnetic material containing element X, element X′, and Mn,wherein the element X′ is at least one element selected from the groupconsisting of Ne, Ar, Kr, Xe, Be, B, C, N, Mg, Al, Si, P, Ti, V, Cr, Fe,Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, Cd, Sn, Hf, Ta, W, Re, Au, Pb,and rare earth elements.

[0090] Preferably, a type of element capable of entering intointerstices in the lattice formed by X and Mn and making an interstitialsolid solution or a type of element capable of displacing some of thelattice points in the crystal lattice formed by X and Mn and making asubstitutional solid solution is used as the element X′, Herein, “solidsolution” refers to a solid in which components thereof arehomogeneously mixed within a single crystal phase.

[0091] By making the material into an interstitial solid solution orsubstitutional solid solution, the lattice constant of the X—Mn—X′ alloycan be increased compared to the lattice constant of the above-describedX—Mn alloy, thereby increasing the difference between the latticeconstant of the antiferromagnetic layer 4 and that of a pinned magneticlayer 3, as described below. As a consequence, the structure of theinterface between the antiferromagnetic layer 4 and the pinned magneticlayer 3 can readily enter a lattice-mismatching state. When the elementX′ is the type of element which forms a substitutional solid solution,characteristics as an antiferromagnetic material are degraded if thecontent X′ is excessively high, thus weakening the exchange couplingmagnetic field generated at the interface with the pinned magnetic layer3. In this embodiment, it is preferable to use an inert rare gaselement, namely, at least one element selected from the group consistingof Ne, Ar, Kr, and Xe, capable of forming an interstitial solidsolution, as the element X′. Since the rare gas elements are inertgasses, the antiferromagnetic characteristics will not be affected evenwhen the rare gas elements are contained in the layers. Moreover, gassessuch as Ar have been conventionally used as the sputtering gasses insidesputtering apparatuses and can easily be incorporated into the layer bymerely optimizing the gas pressure.

[0092] It should be noted that when gaseous elements are used as theelement X′, it is difficult to form the layers containing a large amountof X′. A trace amount of a rare gas in the layers will yield adrastically increased exchange coupling magnetic field.

[0093] In the this embodiment, the content of the above-describedelement X′ is preferably in the range of 0.2 to 10 atomic percent andmore preferably in the range of 0.5 to 5 atomic percent. Preferably, theelement X is platinum (Pt) and the Pt—Mn—X′ alloy is used.

[0094] Next, the pinned magnetic layer 3 composed of three layers isformed on the antiferromagnetic layer 4.

[0095] The pinned magnetic layer 3 is composed of a Co layer 11, a Rulayer 12, and a Co layer 13. The magnetization vectors of the Co layer11 and the Co layer 13 are antiparallel to each other due to theexchange coupling magnetic field at the interface with theantiferromagnetic layer 4. This antiparallel state is a so-called“ferri-magnetic coupling state”. By employing such a structure, themagnetization of the pinned magnetic layer 3 can be stabilized and theexchange coupling magnetic field generated at the interface between thepinned magnetic layer 3 and the antiferromagnetic layer 4 can beincreased.

[0096] The thickness of the Co layer 11 is, for example, approximately20 angstroms. The thickness of the Ru layer 12 is, for example,approximately 8 angstroms. The thickness of the Co layer 13 is, forexample, approximately 15 angstroms.

[0097] It should be noted that the pinned magnetic layer 3 need not becomposed of three layers but can be, for example, a single layer. Thelayers 11, 12, and 13 may be formed of materials other than theabove-described magnetic materials.

[0098] A nonmagnetic interlayer 2 is formed on the pinned magnetic layer3. The nonmagnetic interlayer 2 is composed of, for example, copper(Cu). An insulative material such as Al₂O₃ is used if themagnetoresistive element of the this embodiment is a tunnelmagnetoresistive element (TMR element) utilizing the tunnel effect.

[0099] A free magnetic layer 1 comprising two layers is provided on thenonmagnetic interlayer 2.

[0100] The free magnetic layer 1 is formed of two layers, namely, a NiFealloy layer 9 and a Co layer 10. As shown in FIG. 1, the Co layer 10 islocated at the side contacting the nonmagnetic interlayer 2 so as toprevent the diffusion of metal elements or the like at the interfacewith the nonmagnetic interlayer 2 and to increase the rate of change inresistance (ΔR/R).

[0101] The NiFe alloy layer 9 contains, for example, 80 atomic percentNi and 20 atomic percent Fe. The thickness of the NiFe alloy layer 9 is,for example, approximately 45 angstroms and the thickness of the Colayer 10 is approximately 5 angstroms.

[0102] As shown in FIG. 1, a protective layer 7 comprising a nonmagneticmaterial comprising at least one element selected from the groupconsisting of Ta, Hf, Nb, Zr, Ti, Mo, and W is formed on the freemagnetic layer 1.

[0103] Hard bias layers 5 and conductive layers 8 are formed on twosides of the stacked layers from the underlayer 6 to the protectivelayer 7. The bias magnetic field from the hard bias layers 5 orients themagnetization vector of the free magnetic layer 1 in the track widthdirection (the X direction in the drawing).

[0104] The hard bias layers 5 comprise, for example, a cobalt-platinum(Co—Pt) alloy, a cobalt-chromium-platinum (Co—Cr—Pt) alloy, or the like.The conductive layers 8 comprise, for example, α-Ta, Au, Cr, Cu, W, orthe like. In the above-described tunnel magnetoresistive element, one ofthe conductive layers 8 is provided below the free magnetic layer 1 andthe other above the antiferromagnetic layer 4.

[0105] In this embodiment, a back layer comprising a metal material ornonmagnetic metal Cu, Au, or Ag may be formed on the free magnetic layer1. In such a case, the thickness of the back layer is, for example,approximately 12 to 20 angstroms.

[0106] Preferably, the protective layer 7 comprises tantalum (Ta) or thelike. Preferably, the protective layer 7 has an oxidized surface formingan oxide layer.

[0107] When the back layer is provided, the mean free path of theup-spin electrons contributing to the generation of the magnetoresistiveeffect is extended, and by the so-called spin filter effect, theresulting spin-valve magnetic element exhibits an increased rate ofchange in resistance and is thereby capable of reading ahigh-recording-density medium.

[0108] After the above-described layers are deposited, the layers areheat-treated in order to generate an exchange coupling magnetic field(Hex) at the interface between the antiferromagnetic layer 4 and thepinned magnetic layer 3, and to pin the magnetization vector of thepinned magnetic layer 3 in the height direction (the Y direction in thedrawing) by the thus-generated magnetic field. The crystal orientationof the resulting spin-valve thin-film element is as described below.

[0109] The crystal orientation will be described below in connectionwith the exchanged coupling film mainly composed of theantiferromagnetic layer and the ferromagnetic layer (pinned magneticlayer).

[0110] In this embodiment, as described above, the seed layer 22 isprovided under the antiferromagnetic layer 4. The seed layer 22 isformed in such a manner that one of the crystallographically identicalplanes generically described as {111} planes is preferentially alignedin the layer surface. In this manner, the same crystallographicallyidentical plane of the antiferromagnetic layer 4 deposited on the seedlayer 22 will be preferentially aligned parallel to the layer surface.

[0111] For example, when the seed layer 22 has the (−111) planepreferentially aligned parallel to the layer surface, the (−111) planeof the antiferromagnetic layer 4 is also preferentially aligned parallelto the layer surface.

[0112] Moreover, in the pinned magnetic layer 3 deposited on theantiferromagnetic layer 4, the same crystal plane as theantiferromagnetic layer 4 is preferentially aligned parallel to thelayer surface.

[0113] Accordingly, in the seed layer 22, the pinned magnetic layer 3,and the antiferromagnetic layer 4 of this embodiment, one of thecrystallographically identical planes generically described as {111} ispreferentially aligned parallel to the layer surface.

[0114] It should be noted that in this embodiment, it is preferable thatthe crystal plane being preferentially aligned in a direction parallelto the layer surface be one of the crystallographically identical planesdescribed as the {111} planes since these crystal planes are the closestpacked planes. Thermal stability required to withstand increases inambient temperature inside the magnetic head device and increases in thesense current density can be improved when one of thecrystallographically identical planes described as the {111} planes,i.e., the closest packed planes, is aligned in a direction parallel tothe layer surface because, in this manner, the diffusion of atoms in thelayer thickness direction is reduced, the thermal stability of theinterface between these layers is improved, and reliable operation canbe achieved.

[0115] While the same crystal planes are preferentially aligned parallelto the layer surface in the antiferromagnetic layer 4 and the pinnedmagnetic layer 3, a particular crystal axis lying in the crystal planeof each layer is oriented in a different direction between theantiferromagnetic layer 4 and the pinned magnetic layer 3, at leastpartly (see FIG. 14). For example, referring to FIG. 14, the [110] axesin the (111) plane of the antiferromagnetic layer 4 and the pinnedmagnetic layer 3 are oriented in different directions.

[0116]FIG. 14 is a partial isometric view illustrating the crystalorientations of the antiferromagnetic layer and the ferromagnetic layerconstituting the exchange coupling film of this embodiment.

[0117]FIG. 14 illustrates the crystal orientations of theantiferromagnetic layer 4 comprising an antiferromagnetic materialcontaining X and Mn, wherein X is at least one element selected from thegroup consisting of Pt, Pd, Ir, Rh, Ru, and OS, and the pinned magneticlayer (ferromagnetic layer) 3 comprising, for example, a NiFe-type alloyor the like.

[0118] Referring to FIG. 14, the (111) plane of the antiferromagneticlayer 4 is preferentially aligned parallel to the interface with theferromagnetic layer 3. The (111) plane of the ferromagnetic layer 3 isalso preferentially aligned parallel to the interface with theantiferromagnetic layer 4.

[0119] As shown in FIG. 14, the crystal axes running in a directionperpendicular to the (111) crystal plane (the c direction in thedrawing) are the [111] axes. As described above, since both the (111)planes of the antiferromagnetic layer 4 and the ferromagnetic layer 3are preferentially aligned in parallel to the interface, the [111] axisof the antiferromagnetic layer 4 and the [111] axis of the ferromagneticlayer 3 are oriented in the same direction.

[0120] It should be noted here that the [111] axis described above orthe [110] axis described below refers to the crystal axis of theabove-described crystal plane. Equivalent axes of the [111] axis includethe [−111] axis, [11−1] axis, the [1−11] axis, the [−1−11] axis, the[1−1−1] axis, the [−11−1] axis, and the [−1−1−1] axis. Equivalent axesof the [110] axis include [−110] axis, the [1−10] axis, the [−1−10]axis, the [−10−1] axis, the [101] axis, the [101] axis, the [10−1]axis,the [011] axis, the [01−1] axis, the [0−11] axis, and the [0−1−1] axis.When one of these crystallographically equivalent axes are referred to,the generic notation such as <111> axes or <110> axes will be used.

[0121] In FIG. 14, the [110] axis lying in the (111) plane of theantiferromagnetic layer 4 is oriented in the a direction in the drawing.

[0122] In contrast, the [110] axis lying in the (111) plane of theferromagnetic layer 3 is not oriented in the a direction but is shiftedfrom the a direction toward the b direction in the drawing. As apparentfrom the drawing, the [110] axis of the antiferromagnetic layer 4 andthe [110] axis of the ferromagnetic layer 3 are oriented in differentdirections.

[0123] When the layers have such crystal orientations, the arrangementof the atoms constituting the antiferromagnetic layer 4 and thearrangement of the atoms constituting the ferromagnetic layer 3 areprevented from exhibiting a one-to-one correspondence at the interface.

[0124] When such crystal orientations are achieved, theantiferromagnetic layer 4 will properly transform into an orderedlattice as a result of heat treatment without being restrained by thecrystal structure of the ferromagnetic layer 3, thereby generating anincreased exchange coupling magnetic field.

[0125] The development of such crystal orientations are considered todepend on the conditions at which the pinned magnetic layer 3 and theantiferromagnetic layer 4 are deposited prior to a heating step.

[0126] For example, when components of the antiferromagnetic layer 4 andthe ratio of the components therein are optimized so that the latticeconstants of the antiferromagnetic layer 4 are sufficiently larger thanthe lattice constants of the pinned magnetic layer 3, the layers barelyachieve epitaxial growth.

[0127] If the antiferromagnetic layer 4 and the pinned magnetic layer 3are epitaxially grown, the resulting antiferromagnetic layer 4 and thepinned magnetic layer 3 are likely to have every crystal orientationparallel to each other. Not only are the same crystal planes of theantiferromagnetic layer 4 and the pinned magnetic layer 3 preferentiallyaligned parallel to the interface, but also the above-describedparticular crystal axes in the crystal planes of the antiferromagneticlayer 4 and the pinned magnetic layer 3 are oriented in the samedirection. As a result, the atomic configuration of theantiferromagnetic layer 4 and that of the pinned magnetic layer 3readily exhibit a one-to-one correspondence (see FIG. 15). FIG. 15 showsa specific example in which the [110] axis in the (111) plane of anantiferromagnetic layer 31 is oriented in the same direction as that ofa ferromagnetic layer 30.

[0128]FIG. 15 is a partial isometric view illustrating the crystalorientations of the antiferromagnetic layer and the ferromagnetic layer(pinned magnetic layer) constituting an exchange coupling film(single-valve film) for comparison.

[0129] Reference numeral 31 denotes an antiferromagnetic layercomprising an antiferromagnetic material containing X and Mn, wherein Xis at least one element selected from the group consisting Pt, Pd, Ir,Rh, Ru, and Os. Reference numeral 30 denotes a ferromagnetic layercomprising, for example, a NiFe-type alloy.

[0130] Referring to FIG. 15, the (111) planes of the antiferromagneticlayer 31 and the ferromagnetic layer 30 are preferentially alignedparallel to the layer surface as in the exchange coupling film shown inFIG. 14.

[0131] Because the (111) planes of the antiferromagnetic layer and theferromagnetic layer are preferentially aligned parallel to the layersurface, the [111] axes lying in the (111) planes are oriented in thesame direction, namely, the c direction in the drawing.

[0132] Moreover, in this exchange coupling film for comparison, the[110] axes among the crystal axes in the above-described (111) planes ofthe antiferromagnetic layer 31 and the ferromagnetic layer 30 areoriented in the same direction, namely, the a direction in the drawing.

[0133] Such crystal orientations readily develop in the exchangecoupling film when the antiferromagnetic layer 31 and the ferromagneticlayer 30 are epitaxially grown during their deposition step. When thelayers are epitaxially deposited, not only the same crystal plane ispreferentially oriented parallel to the layer surface in theantiferromagnetic layer 31 and the ferromagnetic layer 30, but alsoother crystal planes not parallel to the layer surface readily enter aparallel relationship between the antiferromagnetic layer 31 and theferromagnetic layer 30.

[0134] Such crystal orientations lead to the development of a one-to-onecorrespondence of the atoms constituting the antiferromagnetic layer 31and the ferromagnetic layer 30 at the interface of these layers. As aconsequence, when such crystal orientations are developed, theantiferromagnetic layer 31 is restrained by the crystal structure of theferromagnetic layer 30 and will not achieve a proper ordertransformation, resulting in a reduced exchange coupling magnetic field.

[0135] If the antiferromagnetic layer 4 and the pinned magnetic layer 3have such crystal orientations, as shown in FIG. 15, before heattreatment, the crystal structure of the antiferromagnetic layer 4 isrestrained by the crystal structure of the pinned magnetic layer 3during heating, the antiferromagnetic layer 4 cannot achieve a properorder transformation, and the exchange coupling magnetic field issignificantly reduced.

[0136] In this embodiment, the antiferromagnetic layer 4 and the pinnedmagnetic layer 3 are not epitaxially deposited. Consequently, theresulting antiferromagnetic layer 4 will not be restrained by thecrystal structure of the pinned magnetic layer 3 and will achieve aproper order transformation once the deposited layers are heated.Observations of the layer structure of the spin-valve film of thepresent invention show that although the same crystallographicallyidentical plane is preferentially aligned parallel to the layer surfacein the antiferromagnetic layer 4 and the pinned magnetic layer 3, othercrystal planes of the antiferromagnetic layer 4 not parallel to thelayer surface are not aligned parallel to those of the pinned magneticlayer 3. As a result, a particular crystal axis in the crystal plane ofthe antiferromagnetic layer 4 is oriented in a direction different fromthat of the pinned magnetic layer 3, at least partly.

[0137] In this embodiment, the seed layer 22 is provided under theantiferromagnetic layer 4 as a means for yielding the above-describedcrystal orientation. As described earlier, by providing the seed layer22, the crystal planes of the upper gap layer antiferromagnetic layer 4and the pinned magnetic layer 3 preferentially aligned parallel to thelayer surface are crystallographically identical. Such a crystalalignment will yield high rates of change in resistance (ΔR/R).

[0138] Also, in this embodiment, a particular crystal axis lying in theabove-described crystal plane of the antiferromagnetic layer 4, thecrystal plane being aligned parallel to the layer surface, and the samecrystal axis of the pinned magnetic layer 3 are oriented in directionsdifferent from each other. Such crystal orientations are considered tohave been developed by a proper transformation from a disordered-phaseface-centered cubic lattice to an ordered-phase Cu—Au—I-type facecentered cubic lattice at the antiferromagnetic layer 4 which is notrestrained by the crystal structure of the pinned magnetic layer 3during heating. As a result, a strong exchange coupling magnetic fieldcan be obtained. Note that in this embodiment, not all, but only part ofthe crystals of the antiferromagnetic layer 4 need to have theCuAu—I-type ordered face-centered cubic lattice after the heattreatment.

[0139] Whether or not the above-described crystal orientations areachieved can be determined by the observation of the cross-sectionsobtained by cutting the pinned magnetic layer 3 and theantiferromagnetic layer 4 in the layer thickness direction (the Zdirection in the drawing).

[0140] In this embodiment, the crystal grain boundaries of theantiferromagnetic layer 4 and the pinned magnetic layer 3 as observed inthe above-described cross-section are discontinuous, at least partially,at the interface between the pinned magnetic layer 3 and theantiferromagnetic layer 4.

[0141]FIG. 26 is a transmission electron microscopy photograph (TEMphotograph) and FIG. 28 is an illustration of the photograph in FIG. 26.As shown in FIGS. 26 and 28, the crystal grain boundaries D and E formedin the PtMn alloy layer (antiferromagnetic layer 4) and the crystalgrain boundaries A, B, and C formed above the antiferromagnetic layerare discontinuous at the interface. When there is such a discontinuity,it can be assumed that the same particular crystal axis lying in thecrystal plane of the antiferromagnetic layer 4 parallel to the layersurface is oriented in a direction different from that of the pinnedmagnetic layer 3, at least partly.

[0142] The crystal structure shown in FIGS. 26 and 28 is clearlydifferent from the crystal structure of the deposited layer shown forcomparison in FIGS. 27 and 29 (FIG. 27 is a transmission electronmicroscopy photograph (TEM photograph) and FIG. 29 is an illustration ofthe photograph in FIG. 27). In FIGS. 27 and 29, the crystal grainboundaries formed in the PtMn alloy layer (antiferromagnetic layer 4)and the crystal grain boundaries formed in the layer above the PtMnalloy layer are continuous since a significantly large crystal grainextending over the interfaces between these layers is formed across theantiferromagnetic layer 4 and the layer provided on theantiferromagnetic layer 4.

[0143] When the exchange coupling film has the crystal grain boundariesof this invention as shown in FIGS. 26 and 28, it is considered that theantiferromagnetic layer 4 and the pinned magnetic layer 3 are notdeposited epitaxially during the deposition process. As a result, aproper order transformation is performed in the antiferromagnetic layer4 without being restrained by the crystal structure of the pinnedmagnetic layer 3, thereby generating an increased exchange couplingmagnetic field.

[0144] In this embodiment, after the antiferromagnetic layer 4 and thepinned magnetic layer 3 are deposited and heated, the crystalorientations thereof are subjected to a transmission electron beamdiffraction analysis. If the diffraction diagrams obtained show theprofiles described below, it can be assumed that the crystal planespreferentially aligned parallel to the interfaces between theantiferromagnetic layer 4 and the pinned magnetic layer 3 arecrystallographically identical and that a particular crystal axis of theantiferromagnetic layer 4 in the above crystal plane is oriented in adirection different from that of the pinned magnetic layer 3, at leastpartly.

[0145] First, an electron beam enters parallel to the interface betweenthe pinned magnetic layer 3 and the antiferromagnetic layer 4. Atransmission electron beam diffraction diagram is obtained for each ofthe antiferromagnetic layer 4 and the pinned magnetic layer 3.

[0146] In the transmission electron beam diffraction diagrams of theantiferromagnetic layer 4 and the pinned magnetic layer 3, diffractionspots corresponding to the reciprocal lattice points assigned torespective crystal planes of the respective layers appear. Thesereciprocal lattice points (diffraction spots) indicate crystal planesdescribed in terms of Miller indices. For example, the reciprocallattice point is the (110) plane.

[0147] Next, each of the diffraction spots is labeled. The range r fromthe beam origin to the diffraction spot is inversely proportional to thelattice interplanar distance d, and d can be obtained by measuring r.Since the interplanar distance of the crystal lattice planes {hkl} ofPtMn, CoFe, NiFe, and the like are resolved to a certain extent, thediffraction spots thereof can be labeled as {hkl} accordingly. Moreover,standard references concerning transmission electron beam diffractionanalysis list transmission electron beam diffraction diagrams obtainedby examining (or calculating) crystal grains of single crystalstructures from various crystal orientations. In each of the diffractiondiagrams, diffraction spots are labeled as {hkl}. By using thesereferences, the resemblance between each of the diffraction spots in thediffraction diagrams of the antiferromagnetic layer 4 and the pinnedmagnetic layer 3, and the diffraction spot of a particular crystal planein a particular single crystal structure is identified, and each of thediffraction spots is labeled accordingly.

[0148] The transmission electron beam diffraction diagram of theantiferromagnetic layer 4 and that of the pinned magnetic layer 3 aresuperimposed on each other while aligning the beam origin of thediffraction diagram of the antiferromagnetic layer 4 with that of thepinned magnetic layer 3.

[0149] Alternatively, the antiferromagnetic layer 4 and the pinnedmagnetic layer 3 may be simultaneously irradiated by the electron beam,and a transmission electron beam diffraction diagram may be obtainedwithin the scope of such irradiation.

[0150] In each of the diffraction diagrams of the pinned magnetic layer3 and the antiferromagnetic layer 4, a particular diffraction spot whichis located in the thickness direction in relation to the beam origin andwhich is given the same label in both the diffraction diagrams of theantiferromagnetic layer 4 and the pinned magnetic layer 3 is selected. Afirst imaginary line is drawn connecting this diffraction spot and thebeam origin. As shown in FIGS. 16 and 18 (FIG. 16 is a transmissionelectron beam diffraction diagram and FIG. 18 is an illustration of thediagram shown in FIG. 16), the first imaginary line in the diffractiondiagram of the pinned magnetic layer 3 and that of the antiferromagneticlayer 4 coincide with each other, indicating the crystal planes of theantiferromagnetic layer 4 and the pinned magnetic layer 3 preferentiallyaligned parallel to the layer surface are crystallographicallyidentical.

[0151] Next, in each of the diffraction diagrams of the pinned magneticlayer 3 and the antiferromagnetic layer 4, a particular diffraction spotwhich is located in a direction other than the above-described layerthickness direction in relation to the beam origin and which is giventhe same label in the diffraction diagrams of the pinned magnetic layer3 and the antiferromagnetic layer 4 is selected. A second imaginary lineis drawn connecting this diffraction spot and the beam origin. As shownin FIGS. 16 and 18, the second imaginary line in the diffraction diagramof the antiferromagnetic layer 4 and the second imaginary line in thediffraction diagram of the pinned magnetic layer 3 are not coincident,indicating the crystal planes of the antiferromagnetic layer 4, whichare not aligned parallel to the layer surface, are not parallel to thecorresponding crystal planes of the pinned magnetic layer 3. Anotherinstance where the crystal planes aligned in a direction other than thelayer surface direction are not parallel with each other between thepinned magnetic layer 3 and the antiferromagnetic layer 4 is when aparticular diffraction spot indicative of a particular crystal plane,located in a direction other than the layer thickness direction, appearsonly in one of the diffraction diagrams.

[0152] The diffraction diagrams obtained from the spin-valve film of thethis embodiment and the diffraction diagrams obtained for comparisonfrom a conventional spin-valve film are clearly different as can beunderstood from FIGS. 17 and 19 (FIG. 17 is a transmission electron beamdiffraction image and FIG. 19 is an illustration of the diffractionimage of FIG. 19). In the comparison spin-valve film, as shown in FIGS.17 and 19, the second imaginary line in the diffraction diagram of theantiferromagnetic layer 4 drawn as above and that of the pinned magneticlayer 3 are coincident with each other.

[0153] When a transmission electron beam diffraction image as in FIG. 16is obtained, it can be assumed that the crystal planes of theantiferromagnetic layer 4 and the pinned magnetic layer 3 alignedparallel to the layer surface are crystallographically identical andthat crystallographically identical axes lying in the crystal planes ofthe antiferromagnetic layer 4 and the pinned magnetic layer 3 areoriented in different directions.

[0154] The diffraction diagrams of the antiferromagnetic layer and theferromagnetic layer will be explained in detail with reference to FIGS.16 to 19.

[0155]FIGS. 16 and 17 are transmission electron beam diffractiondiagrams obtained using an electron beam in a direction perpendicular toa cross-section of the deposited layers (spin-valve film) cut parallelto the layer thickness direction. The transmission electron beamdiffraction diagrams shown in FIG. 16 is obtained using an electron beamhaving an aperture capable of irradiating both the antiferromagneticlayer and the layer other than the antiferromagnetic layer.

[0156]FIG. 18 is an illustration of the transmission electron beamdiffraction diagram shown in FIG. 16. FIG. 19 is an illustration of thetransmission electron beam diffraction diagram shown in FIG. 17.

[0157]FIG. 16 is a transmission electron beam diffraction diagramobtained from the spin-valve film of this embodiment. The spin valvelayer comprises: an Al₂O₃ layer 3 nm in thickness; a Ta layer 3 nm inthickness; a Ni₈₀Fe₂₀ seed layer 2 nm in thickness; a Pt₅₄Mn₄₆antiferromagnetic layer 15 nm in thickness; a pinned magnetic layercomposed of a Co layer 1.5 nm in thickness, a Ru layer 0.8 nm inthickness, and a Co layer 2.5 nm in thickness; a Cu nonmagneticinterlayer 2.5 nm in thickness; a free magnetic layer composed of a Colayer 1 nm in thickness and a Ni₈₀Fe₂₀ layer 3 nm in thickness; a Cuback layer 1.5 nm in thickness; a Ta protective layer 1.5 nm inthickness; and a Ta oxide layer.

[0158]FIG. 17 is an transmission electron beam diffraction diagramobtained for comparison from a conventional spin-valve film. The spinvalve layer comprises: an Al₂O₃ layer 3 nm in thickness; a Ta layer 3 nmin thickness; a Ni₈₀Fe₂₀ seed layer 2 nm in thickness; a Pt₄₄Mn₅₆antiferromagnetic layer 13 nm in thickness; a pinned magnetic layercomposed of a Co layer 1.5 nm in thickness, a Ru layer 0.8 nm inthickness, and a Co layer 2.5 nm in thickness; a Cu nonmagneticinterlayer 2.5 nm in thickness; a free magnetic layer composed of a Colayer 1 nm in thickness and a Ni₈₀Fe₂₀ layer 3 nm in thickness; a Cuback layer 1.5 nm in thickness; a Ta protective layer 1.5 nm inthickness; and a Ta oxide layer.

[0159] Referring to FIG. 16, the diffraction spot indicating the {111}plane of PtMn and the diffraction spot indicating the {111} plane offcc-Co/Cu/NiFe are located on the same line extending in the layerthickness direction. When these diffraction spots are specificallylabeled, for example, (111) planes, the diffraction spots (−111)indicative of the crystal plane which is not parallel to the layersurface but forms 70.5 degrees angle with the (1−11) plane, are not onthe same line extending from the center of the diffraction diagram. Inother words, the crystal planes not parallel to the layer surface do notenter a parallel relationship between the PtMn layer and the pinnedmagnetic layer (ferromagnetic layer).

[0160] Referring to FIG. 17, the diffraction points indicative of {111}planes of PtMn and fcc-Co/Cu/NiFe (fcc-Co pinned magnetic layer isincluded) are on the same line extending in the layer thicknessdirection. Moreover, the diffraction points indicative of {200} planesare on the same line extending from the center of the diagram. The samecan be observed for the diffraction spots other than the above-describeddiffraction spots. The diffraction diagrams of the PtMn and thefcc-Co/Cu/NiFe have every direction analogous. The reason that thediffraction diagram of PtMn is smaller than that of the fcc-Co/Cu/NiFeis that the lattice constant of PtMn is larger than that of thefcc-Co/Cu/NiFe by approximately 10 percent. PtMn and fcc-Co/Cu/NiFeexhibit perfect lattice matching, i.e., an epitaxial relationship.

[0161] It should be noted that in the diffraction diagram shown in FIG.16, a bar (−) is placed on the figure “1” in the notation of the crystalplanes described in terms of Miller indices. This represents −1 (minusone) and is described as “−1” throughout the specification.

[0162] Referring to FIG. 16, in the transmission electron beamdiffraction diagram of this embodiment, a diffraction spot of theantiferromagnetic layer (PtMn) labeled as (1−11) appears in the layerthickness direction. The diffraction spot of layers other than theantiferromagnetic layer (indicated as “fcc-Co/Cu/NiFe” in thediffraction diagram) and labeled as (1−11) also appears in the layerthickness direction.

[0163] The above-described diffraction spots are illustrated in FIG. 18.As is apparent from FIG. 18, the first imaginary line connecting thediffraction spot labeled as the (1−11) plane in the diffraction diagramof the antiferromagnetic layer and the beam origin, and the firstimaginary line connecting the diffraction spot labeled as the (1−11)plane in the diffraction diagram of the layer other than theantiferromagnetic layer are coincident with each other.

[0164] As shown in FIG. 16, a diffraction spot of the antiferromagneticlayer (PtMn layer) labeled as the (−111) plane and located in the adirection other than the layer thickness direction appears in thetransmission electron beam diffraction diagram of this embodiment. In adirection other than the layer thickness direction, the diffraction spotlabeled as the (−111) appears (the diffraction spot is indicated as thefcc-Co/Cu/NiFe in the diffraction diagram).

[0165] However, as the illustration in FIG. 18 shows, the secondimaginary lines connecting the above-described diffraction spots and thebeam origin are not coincident with each other.

[0166] Thus, it can be understood from the electron beam, diffractiondiagram of this embodiment that, in the antiferromagnetic layer and theferromagnetic layer, one of the crystallographically identical planesgenerically described as the {111} planes is preferentially alignedparallel to the layer thickness, but the crystal planes other than theones aligned parallel to the layer surface are not in a parallelrelationship between the antiferromagnetic layer and the ferromagneticlayer.

[0167] It should be noted that, although the diffraction point assignedto the (−111) plane, i.e., the diffraction point located in a directionother than the layer thickness direction, appears in both theantiferromagnetic layer and the ferromagnetic layer, there may be aninstance where the (−111) diffraction point appears in only one of thelayers in the diffraction diagrams. An example of such an instance iswhen the crystal orientation of one layer is further rotated on an axisin the layer thickness direction from the crystal orientation of theother layer. In this case also, the crystal planes not aligned parallelto the layer surface are not in a parallel relationship between theantiferromagnetic layer and the ferromagnetic layer.

[0168] In contrast, in a transmission electron beam diffraction diagramof the comparison spin-valve film shown in FIG. 17, the diffraction spotindicative of the {111} plane of the antiferromagnetic layer (PtMn)appears in the layer thickness direction. The diffraction spotindicative of the {111} plane of a layer other than theantiferromagnetic layer (referred to as the fcc-Co/Cu/NiFe in theelectron beam diffraction diagram) appears in the same layer thicknessdirection.

[0169] It should be noted here that, in the diffraction diagram shown inFIG. 17, the diffraction spots are labeled as family including all thecrystallographically identical planes, namely {111} planes, instead of(111) plane or (11−1) plane. The notation in FIG. 17 is different fromthe notation in FIG. 16, but unlike FIG. 16, the [111] diffraction spotslocated in a direction other than the layer thickness direction (forexample, (−111)) do not require an explanation.

[0170] Moreover, as is apparent from the transmission electron beamdiffraction diagram of the comparison spin-valve film shown in FIG. 17,a diffraction spot indicative of the {200} plane of theantiferromagnetic layer (PtMn) appears in a direction other than thelayer thickness direction. A diffraction spot indicative of the {200}plane of the layer other than the antiferromagnetic layer (in thediagram referred to as “fcc-Co/Cu/NiFe”) appears in a direction otherthan the layer thickness direction.

[0171] As is apparent from the illustration shown in FIG. 19, in thecomparison transmission electron beam diffraction diagram, a diffractionspot indicative of the {111} plane of the antiferromagnetic layer andthe ferromagnetic layer appears in the layer thickness direction whenviewed from the beam origin. The first imaginary lines connecting thediffraction points and the beam origin are coincident with each other inthe diffraction diagrams of the antiferromagnetic layer and theferromagnetic layer. Also, the second imaginary lines connecting thebeam origin and the diffraction spots indicative of the {200} planelocated in a direction other than the layer thickness direction whenviewed from the beam origin are coincident with each other in thediffraction diagrams of the antiferromagnetic layer and theferromagnetic layer.

[0172] In other words, in the comparison diffraction diagram, thecrystal planes not aligned in the layer surface direction are in aparallel relationship between the antiferromagnetic layer and theferromagnetic layer as a result of epitaxial deposition. The atomicarrangement of the antiferromagnetic layer and the atomic arrangement ofthe ferromagnetic layer readily enter into a one-to-one correspondence(the lattice-matching state) at the interface between theantiferromagnetic layer and the ferromagnetic layer. When there is alattice-matching, a proper order transformation does not occur in theantiferromagnetic layer by the heat treatment, thus generating a reducedexchange coupling magnetic field.

[0173] The exchange coupling magnetic field (Hex) of the spin-valve filmhaving the layer configuration according to the film for comparison ismeasured, and a low exchange coupling magnetic field of approximately0.24×10⁴ (A/m) is obtained.

[0174] In contrast, in this embodiment of the present invention,although the crystallographically identical planes are preferentiallyaligned parallel to the interface of the antiferromagnetic layer and theferromagnetic layer, other crystal planes do not enter a parallelrelationship between the antiferromagnetic layer and the ferromagneticlayer. As if the crystal orientations of the antiferromagnetic layer andthe ferromagnetic layer are rotated about an axis perpendicular to theinterface, the axes lying in these crystal planes preferentially alignedparallel to the interface are not oriented in the same direction betweenthe antiferromagnetic layer and the ferromagnetic layer, at leastpartly.

[0175] As a result, the atomic arrangement of the antiferromagneticlayer and the atomic arrangement of the ferromagnetic layer do notexhibit a one-to-one correspondence. A proper order transformationoccurs in the antiferromagnetic layer without being restrained by thecrystal structure of the ferromagnetic layer when the antiferromagneticlayer is heat-treated, and an increased exchange coupling magnetic fieldcan be obtained compared to the conventional technique.

[0176] The intensity of the exchange coupling magnetic field (Hex)obtained from the spin-valve film of the present invention is measuredand a significantly high exchange coupling magnetic field of 10.9×10⁴(A/m) is obtained.

[0177] When the spin-valve film is capable of yielding the transmissionelectron beam diffraction image in FIGS. 16 and 18, a proper ordertransformation has taken place in the antiferromagnetic layer 4 as aresult of heat treatment and a strong exchange coupling magnetic fieldcan be obtained.

[0178] It should be noted here that the diffraction spot located in theabove-described layer thickness direction is preferably the diffractionspot indicative of crystal planes generically described as {111}.

[0179] The crystal orientation of the antiferromagnetic layer 4 and thepinned magnetic layer 3 is further observed by transmission electronbeam diffraction from an angle different from the above. When theobtained transmission electron beam diffraction images are as describedbelow, it can be assumed that the crystal planes of theantiferromagnetic layer 4 and the pinned magnetic layer 3 alignedparallel to the layer surface are crystallographically identical andthat a particular crystal axis lying in the crystal plane of theantiferromagnetic layer 4 and the same axis lying in the crystal planeof the pinned magnetic layer 3 are oriented, at least partly, indifferent directions.

[0180] First, an electron beam enters from a direction perpendicular tothe interface between the antiferromagnetic layer 4 and the pinnedmagnetic layer 3. The transmission electron beam diffraction diagrams ofthe antiferromagnetic layer 4 and that of the pinned magnetic layer 3are obtained simultaneously. The obtained diagrams are shown in FIGS. 20and 21. FIG. 20 is an illustration of the diffraction image of theantiferromagnetic layer 4 and FIG. 21 is an illustration of thediffraction image of the pinned magnetic layer 3.

[0181] In the transmission electron beam diffraction diagrams of theantiferromagnetic layer 4 and the pinned magnetic layer 3, thediffraction spots indicative of the same reciprocal lattice planesappear. Such reciprocal lattice planes, i.e., the projection planes ofthe electron beam diffraction image, are parallel to the crystal planeand perpendicular to the incident electron beam. An example of thecrystal plane parallel to the above-described reciprocal lattice planeis the (111) plane. In this embodiment, the crystallographicallyidentical axes generically described as <111> are preferably oriented ina direction perpendicular to the interface between the pinned magneticlayer 3 and the antiferromagnetic layer 4. Moreover, the crystal planesparallel to the above-described interface between the antiferromagneticand the ferromagnetic layers are preferably crystallographicallyidentical planes generically described as the {111} planes.

[0182] Next, using references showing the transmission electron beamdiffraction diagrams of various single crystals, each of the diffractionspots is labeled. Since there is a difference between the latticeconstants of the antiferromagnetic layer 4 and the pinned magnetic layer3, i.e., between the lattice interplanar distances thereof, thetransmission electron beam diffraction spots of the antiferromagneticlayer 4 can be easily discriminated from those of the pinned magneticlayer 3 by examining the distances between the respective diffractionspots and the beam origin (see FIG. 22).

[0183] With reference to FIG. 22, first and third imaginary linesconnecting the beam origin and a particular diffraction spot given aparticular label in the diffraction diagram of the antiferromagneticlayer 4 are not coincident with the second and fourth imaginary linesconnecting the beam origin and the diffraction spot, given the samelabel, of the pinned magnetic layer 3, indicating thatcrystallographically identical axes lying in the crystal planes alignedparallel to the layer surface are oriented in different directionsbetween the antiferromagnetic layer 4 and the pinned magnetic layer 3.Another indication that the crystallographically identical axes lying inthe crystal planes aligned parallel to the layer surface are oriented indifferent directions between the antiferromagnetic layer 4 and thepinned magnetic layer 3 is when a diffraction spot given a particularlabel only appears in one of the diffraction diagrams of the pinnedmagnetic layer 3 and the antiferromagnetic layer 4.

[0184] The transmission electron beam diffraction diagrams obtainedusing an electron beam perpendicular to the interface will be describedin particular detail with reference to FIGS. 20 to 22.

[0185] FIGS. 20 to 22 are perspective illustrations of theabove-described transmission electron beam diffraction diagrams.

[0186] The transmission electron beam diffraction pattern shown in FIG.20 illustrates the electron beam diffraction pattern of a PtMn crystal.FIG. 21 illustrates the electron beam diffraction pattern of a crystalin the ferromagnetic layer (fcc-Co). FIG. 22 is an illustrationcombining the diagrams in FIGS. 20 and 21 aligning on the diffractionspot (000) (the beam origin) of each diagram.

[0187] The black dots in FIG. 20 indicate diffraction spots. Each of thediffraction spots is labeled. The circles in FIG. 21 indicatediffraction spots, each of which is also labeled.

[0188] As shown in FIG. 20, the crystal axis connecting the beam origin(000) and the diffraction spot (−2−24) is the [−1−12] axis. The crystalaxis connecting the beam origin (000) and the diffraction spot (2−20) isthe [1−10] axis.

[0189] The same labeling is performed in the diffraction pattern shownin FIG. 21. Although the [−1−12] axis and the [1−10] axis are indicated,these crystal axes are oriented in a direction different from thecorresponding crystal axes shown in FIG. 20.

[0190] As is apparent from the combined diffraction diagram in FIG. 22aligning the diffraction patterns of FIGS. 20 and 21, a first imaginaryline connecting the diffraction spot (−2−24 of the antiferromagneticlayer and the beam origin (000), and a second imaginary line connectingthe diffraction spot (−2−24) and the beam origin (000) are notcoincident with each other. A third imaginary line connecting thediffraction spot (2−20) of the antiferromagnetic layer and the beamorigin (000), and a fourth imaginary line connecting the beam origin andthe diffraction spot (2−20) of the ferromagnetic layer, are notcoincident with each other.

[0191] It can be understood from the above-described transmissionelectron beam diffraction diagrams that the crystal planes of theantiferromagnetic layer and the ferromagnetic layer preferentiallyaligned parallel to the layer surface are crystallographically identicaland that the crystallographically identical crystal axes lying in thesecrystal planes are oriented in different directions between theantiferromagnetic layer and the ferromagnetic layer. In other words, thecrystal planes not aligned parallel to the layer surface, and are not ina parallel relationship between the antiferromagnetic layer and theferromagnetic layer.

[0192] FIGS. 23 to 25 are transmission electron beam diffractiondiagrams obtained from the comparison spin-valve film. FIG. 23 is atransmission electron beam diffraction diagram of a crystal in theantiferromagnetic layer (PtMn). FIG. 24 is a transmission electron beamdiffraction diagram of a crystal in the ferromagnetic layer (fcc-Co).FIG. 25 is a diffraction pattern combining the diffraction diagrams ofFIGS. 23 and 24 while aligning the beam origin.

[0193] As shown in FIGS. 23 and 24, the [−1−12] axes each connecting thebeam origin and the diffraction spot (−2−24) in the antiferromagneticlayer and the ferromagnetic layer are oriented in the same direction.The [1−10] axes each connecting the beam origin and the diffraction spot(2−20) are also oriented in the same direction between theantiferromagnetic layer and the ferromagnetic layer.

[0194] In other words, as shown in FIG. 25, the fifth imaginary lineseach connecting the beam origin and the diffraction spot (−2−24) arecoincident with each other in the diffraction diagrams of theantiferromagnetic layer and the ferromagnetic layer. The sixth imaginarylines each connecting the beam origin and the diffraction spot (2−20)are also coincident with each other in the diffraction diagrams of theantiferromagnetic layer and the ferromagnetic layer.

[0195] In the comparison spin-valve film, not only are the crystalplanes preferentially aligned parallel to the layer surfacecrystallographically identical in the antiferromagnetic layer and theferromagnetic layer, but the crystallographically identical axes lyingin these crystal planes are also perfectly coincident with each otherbetween the antiferromagnetic layer and the ferromagnetic layer.Consequently, the crystal planes other than the ones aligned parallel tothe layer surface are in a parallel relationship between theantiferromagnetic layer and the ferromagnetic layer.

[0196] The diffraction diagrams obtained from the spin-valve film of thethis embodiment and the diffraction diagrams obtained from thecomparison spin-valve film are clearly different, as can be understoodfrom FIGS. 23 to 25.

[0197] When transmission electron beam diffraction diagrams as in FIGS.20 to 22 are obtained, it can be assumed that the crystal planes of theantiferromagnetic layer 4 and the pinned magnetic layer 3 alignedparallel to the layer surface are crystallographically identical andthat a particular crystal axis lying in the crystal plane of theantiferromagnetic layer 4 and the crystallographically identical axislying in the crystal plane of the pinned magnetic layer 3 are oriented,at least partly, in different directions.

[0198] When the spin-valve film is capable of yielding the transmissionelectron beam diffraction diagrams as in FIGS. 20 to 22, a proper ordertransformation has occurred in the antiferromagnetic layer 4 duringheating. As a result, a strong exchange coupling magnetic field can beobtained.

[0199] Next, in order to prepare a spin-valve thin-film magnetic elementhaving the above-described crystal orientations and crystal grainboundaries, the antiferromagnetic layer 4 and the pinned magnetic layer3 need to be in a lattice-mismatching state after deposition thereof.

[0200] The lattice-mismatching state refers to a state in which theatomic configuration of the antiferromagnetic layer 4 does not show aone-to-one correspondence with the atomic configuration of the pinnedmagnetic layer 3 at the interface therebetween. In order to yield such alattice-mismatching state, it is necessary to make the lattice constantof the antiferromagnetic layer 4 larger than the lattice constant of thepinned magnetic layer 3.

[0201] In addition, the antiferromagnetic layer 4 is required to undergoa proper order transformation as a result of a heat treatment. Theintensity of the generated exchange coupling magnetic field will be lowif the antiferromagnetic layer 4 does not undergo the ordertransformation even if the lattice-mismatching state is obtained at theinterface.

[0202] In order to bring about the lattice-mismatching state during thedeposition step and to achieve an order transformation, the ratio ofeach component composing the antiferromagnetic layer 4 is important.

[0203] In this embodiment, the X or X+X′ content is preferably in therange of 45 to 60 atomic percent. In this manner, thelattice-mismatching state can be achieved at the interface with thepinned magnetic layer 3 and a proper order transformation will takeplace in the antiferromagnetic layer 4 by heating.

[0204] In the spin-valve thin-film element using the antiferromagneticlayer 4 formed according to the above-described ratio, the crystalplanes of the antiferromagnetic layer 4 and the pinned magnetic layer 3preferentially aligned parallel to the layer surface can be incrystallographically identical planes. It is also possible to orientparticular crystallographically identical axes lying in the crystalplane of the antiferromagnetic layer 4 in a direction different fromthat of the pinned magnetic layer 3, at least partly. Moreover, it ispossible to make the crystal grain boundaries of the antiferromagneticlayer 4 discontinuous with the crystal grain boundaries of the pinnedmagnetic layer 3, at least partly. When the above-described ratio ismet, an exchange coupling magnetic field of more than 1.5810⁴ (A/m) canbe generated, as shown in the experimental example described below.

[0205] Preferably, the content of element X or the total content ofelements X and X′ is in the range of 49 to 56.5 atomic percent. In thismanner, an exchange coupling magnetic field of 7.9×10⁴ (A/m) or more canbe generated.

[0206] According to the spin-valve thin-film element having theabove-described crystal orientations, it is possible to put at leastpart of the interface between the pinned magnetic layer 3 and theantiferromagnetic layer 4 into a lattice-mismatching state after theheat treatment.

[0207] The same crystal structure and the transmission electron beamdiffraction diagram as in the interface between the antiferromagneticlayer 4 and the pinned magnetic layer 3 are also achieved at theinterface between the seed layer 22 and the antiferromagnetic layer 4.That is, at the interface between the seed layer 22 and theantiferromagnetic layer 4, crystallographically identical planes arepreferentially aligned parallel to the layer surface, andcrystallographically identical axes lying in these crystal plane areoriented in different directions between the seed layer 22 and theantiferromagnetic layer 4, at least partly.

[0208] Moreover, in a cross-section parallel to the layer thicknessdirection, the crystal grain boundaries of the seed layer 22 and thoseof the antiferromagnetic layer 4 are discontinuous at the interface, atleast partly.

[0209] When the seed layer 22 and the antiferromagnetic layer 4 havesuch crystal orientations and crystal grain boundaries, it is easy forat least part of the interface between the seed layer 22 and theantiferromagnetic layer 4 to maintain the lattice-mismatching state. Asa result, a proper order transformation will occur in theantiferromagnetic layer 4 without being restrained by the crystalstructure of the seed layer 22, thereby generating a strong exchangecoupling magnetic field.

[0210] In this embodiment, the thickness of the antiferromagnetic layer4 is preferably in the range of 7 nm to 30 nm. According to theembodiment, a sufficiently strong exchange coupling magnetic field canbe generated even when the thickness of the antiferromagnetic layer 4 isreduced to the above range.

[0211]FIG. 2 is a sectional view showing a part of the structure of aspin-valve thin-film element according to a second embodiment of thepresent invention.

[0212] This spin-valve thin-film element comprises: an underlayer 6; afree magnetic layer 1 comprising a NiFe alloy layer 9 and a Co layer 10;a nonmagnetic interlayer 2, and a pinned magnetic layer 3 comprising aCo layer 11, a Ru layer 12, a Co layer 13; an antiferromagnetic layer 4;and a protective layer 7, deposited on that order. Hard bias layers 5and conductive layers 8 are provided on two sides of the depositedlayers.

[0213] Each of the above layers is composed of the same material as inthe first embodiment of the spin-valve thin-film element shown in FIG.1.

[0214] In the antiferromagnetic layer 4 and the pinned magnetic layer 3of the spin-valve thin-film element shown in FIG. 2, the crystal planesof the antiferromagnetic layer 4 and the pinned magnetic layer 3preferentially aligned parallel to the layer surface arecrystallographically identical, and particular crystallographicallyidentical crystal axes lying in these crystal planes of theantiferromagnetic layer 4 and the pinned magnetic layer 3 are orientedin different directions, at least partly.

[0215] Moreover, in a cross-section of the antiferromagnetic layer 4 andthe pinned magnetic layer 3 parallel to the layer thickness direction(the Z direction in the drawing), the crystal grain boundaries of theantiferromagnetic layer 4 and those of the pinned magnetic layer 3 arediscontinuous at the interface, at least partly.

[0216] As a result, at least part of the above interface keeps thelattice-mismatching state, a proper order transformation can be achievedin the antiferromagnetic layer 4 as a result of the heat treatment, andan increased exchange coupling magnetic field can be obtained.

[0217] Preferably, the crystal planes of the antiferromagnetic layer 4and the pinned magnetic layer 3 preferentially aligned parallel to thelayer surface are the crystallographically identical planes genericallydescribed as the {111} planes. Preferably, the crystallographicallyidentical axes generically described as the <110> axes are oriented indifferent directions between the antiferromagnetic layer 4 and thepinned magnetic layer 3.

[0218] In the spin-valve thin-film element shown in FIG. 2, diffractionspots corresponding to the reciprocal lattice points indicative ofcrystal planes of the antiferromagnetic layer 4 and the pinned magneticlayer 3 appear in transmission electron beam diffraction diagrams of theantiferromagnetic layer 4 and the pinned magnetic layer 3 using anelectron beam entering in a direction parallel to the interface thereof.One diffraction spot which is given the same label and being located inthe layer thickness direction when viewed from the beam origin isselected and a first imaginary line connecting the diffraction spot andthe beam origin is drawn for each of the diffraction diagrams. The firstimaginary line in the diffraction diagram of the pinned magnetic layer 3and the first imaginary line in the diffraction diagram of theantiferromagnetic layer 4 are coincident with each other.

[0219] Moreover, a second imaginary line in the diffraction diagram ofthe antiferromagnetic layer 4, connecting the beam origin and adiffraction spot indicative of a particular crystal plane and located ina direction other than the layer thickness direction when viewed fromthe beam origin does not coincide with a second imaginary line drawn inthe same manner in the diffraction diagram of the pinned magnetic layer3. In other cases, the diffraction spot indicative of a certain crystalplane and located in a direction other than the layer thicknessdirection appears in only one of the diffraction diagrams of theantiferromagnetic layer and ferromagnetic layer.

[0220] The diffraction spot located in the layer thickness direction ispreferably the one indicating one of the crystallographically identicalplanes generically described as the {111} planes.

[0221] Furthermore, in the spin-valve thin-film element shown in FIG. 2,diffraction spots corresponding to the reciprocal lattice pointsindicative of the crystal planes of the pinned magnetic layer 3 and theantiferromagnetic layer 4 appear in the transmission electron beamdiffraction diagrams obtained using an electron beam entering from adirection perpendicular to the interface between the antiferromagneticlayer 4 and the pinned magnetic layer 3. Among the diffraction spots,one diffraction spot given the same label in the diffraction diagrams ofthe pinned magnetic layer 3 and the antiferromagnetic layer 4 isselected and a imaginary line connecting the diffraction spot and thebeam origin is drawn for each of the diffraction diagrams. The imaginarylines are not coincident with each other at the diffraction diagrams ofthe pinned magnetic layer 3 and that of the antiferromagnetic layer 4.In other cases, the diffraction spot appears in only one of thediffraction diagrams of the antiferromagnetic layer 4 and the pinnedmagnetic layer 3.

[0222] Preferably, the direction perpendicular to the above-describedinterface is the direction of the crystallographically identical axesgenerically described as the <111> axes. Moreover, the crystal planespreferentially aligned parallel to the interface between theantiferromagnetic layer and the ferromagnetic layer are preferably thecrystallographically identical planes generically described as the {111}planes.

[0223] When the transmission electron beam diagrams as described aboveare obtained, it can be assumed that the crystal planes of theantiferromagnetic layer 4 and the pinned magnetic layer 3 preferentiallyaligned parallel to the layer surface are crystallographically identicaland that particular crystallographically identical crystal axes lying inthese crystal planes of the antiferromagnetic layer 4 and the pinnedmagnetic layer 3 are oriented in different directions, at least partly.

[0224] Also, in the spin-valve thin-film element having theabove-described transmission electron beam diffraction diagrams, aproper order transformation occurs in the antiferromagnetic layer 4 as aresult of heat treatment, and an increased coupling magnetic fieldcompared to the conventional technique can be obtained.

[0225] In the spin-valve thin-film element shown in FIG. 2, the contentX or the total content X and X′ constituting the antiferromagnetic layer4 is preferably in the range of 45 to 60 atomic percent. In this manner,an exchange coupling magnetic field of 1.58×10⁴ (A/m) or more can beobtained.

[0226] More preferably, the X or X+X′ content is preferably in the rangeof 49 to 57 atomic percent. In this manner, an exchange couplingmagnetic field of 7.9×10⁴ (A/m) or more can be obtained.

[0227]FIG. 3 is a cross-sectional view showing part of the structure ofa spin-valve thin-film element according to a third embodiment of thepresent invention.

[0228] Referring to FIG. 3, an underlayer 6, a seed layer 22, anantiferromagnetic layer 4, a pinned magnetic layer 3, a nonmagneticinterlayer 2, and a free magnetic layer 1 are deposited in that orderfrom the bottom.

[0229] The underlayer 6 preferably comprises at least one elementselected from the group consisting of Ta, Hf, Nb, Zr, Ti, Mo, and W.

[0230] Preferably, the seed layer 22 has a face-centered cubic crystalstructure and has one of the crystallographically identical planesgenerically described as the {111} planes preferentially alignedparallel to the interface with the antiferromagnetic layer 4. Thematerial thereof and other factors regarding the seed layer 22 areidentical to the first embodiment shown in FIG. 1.

[0231] When the seed layer 22 is provided under the antiferromagneticlayer 4, each of the antiferromagnetic layer 4, the pinned magneticlayer 3, the nonmagnetic interlayer 2, and the free magnetic layer 1deposited thereon has the same crystallographically identical planespreferentially aligned parallel to the layer surface.

[0232] As shown in FIG. 3, the pinned magnetic layer 3 comprises threelayers, namely Co layers 11 and 13 and a Ru layer 12. Alternatively, thepinned magnetic layer 3 may be formed of other materials and may becomposed of, for example, one layer instead of three.

[0233] Although the free magnetic layer 1 comprises two layers, namely aNiFe alloy layer 9 and a Co layer 10, in this embodiment, the freemagnetic layer 1 may be formed of other materials and may be composedof, for example, one layer instead of two layers.

[0234] In the spin-valve thin-film element shown in FIG. 3, the crystalplanes of the antiferromagnetic layer 4 and the pinned magnetic layer 3preferentially aligned parallel to the layer surface arecrystallographically identical and that particular crystallographicallyidentical crystal axes lying in these crystal planes of theantiferromagnetic layer 4 and the pinned magnetic layer 3 are orientedin different directions, at least partly.

[0235] Moreover, in a cross-section of the antiferromagnetic layer 4 andthe pinned magnetic layer 3 parallel to the layer thickness direction(the Z direction in the drawing), the crystal grain boundaries of theantiferromagnetic layer 4 and those of the pinned magnetic layer 3 arediscontinuous at the interface, at least partly.

[0236] As a result, at least part of the interface keeps thelattice-mismatching state. A proper order transformation occurs in theantiferromagnetic layer 4 as a result of heat treatment and a strongexchange coupling magnetic field can be obtained.

[0237] Preferably, the crystal planes of the antiferromagnetic layer 4and the pinned magnetic layer 3 preferentially aligned parallel to thelayer surface are the crystallographically identical planes genericallydescribed as the {111} planes. Preferably, the crystallographicallyidentical axes generically described as the <110> axes are oriented indifferent directions between the antiferromagnetic layer 4 and thepinned magnetic layer 3.

[0238] In the spin-valve thin-film element shown in FIG. 3, diffractionspots corresponding to the reciprocal lattice points indicative ofcrystal planes of the antiferromagnetic layer 4 and the pinned magneticlayer 3 appear in transmission electron beam diffraction diagrams of theantiferromagnetic layer 4 and the pinned magnetic layer 3 using anelectron beam entering in a direction parallel to the interface thereof.One diffraction spot given the same label and being located in the layerthickness direction when viewed from the beam origin is selected and afirst imaginary line connecting the diffraction spot and the beam originis drawn for each of the diffraction diagrams. The first imaginary linein the diffraction diagram of the pinned magnetic layer 3 and the firstimaginary line in the diffraction diagram of the antiferromagnetic layer4 are coincident with each other.

[0239] Moreover, in this embodiment, a second imaginary line in thediffraction diagram of the antiferromagnetic layer, the line connectingthe beam origin and a diffraction spot indicative of a particularcrystal plane and located in the direction other than the layerthickness direction when viewed from the beam origin, does not coincidewith that in the diffraction diagram of the ferromagnetic layer. Inother cases, a diffraction spot indicative of a particular crystal planeand located in a direction other than the layer thickness directionappears only in one of the diffraction diagrams of the antiferromagneticlayer and the ferromagnetic layer.

[0240] Preferably, the diffraction spot located in the thicknessdirection indicates one of the crystallographically identical planesgenerically described as the {111} planes.

[0241] Furthermore, in the spin-valve thin-film element shown in FIG. 3,diffraction spots corresponding to the reciprocal lattice pointsindicative of the crystal planes of the pinned magnetic layer 3 and theantiferromagnetic layer 4 appear in the transmission electron beamdiffraction diagrams obtained using an electron beam entering from adirection perpendicular to the interface between the antiferromagneticlayer 4 and the pinned magnetic layer 3. Among the diffraction spots,one diffraction spot given the same label in the diffraction diagrams ofthe pinned magnetic layer 3 and the antiferromagnetic layer 4 isselected for each of the diffraction diagrams and a imaginary lineconnecting the diffraction spot and the beam origin is drawn for each ofthe diffraction diagrams. The imaginary lines are not coincident witheach other at the diffraction diagrams of the pinned magnetic layer 3and that of the antiferromagnetic layer 4. In other cases, thediffraction spot appears in only one of the diffraction diagrams of theantiferromagnetic layer 4 and the pinned magnetic layer 3.

[0242] The direction perpendicular to the above-described interface ispreferably the direction of the crystallographically identical axesgenerically described as the <111> direction. Moreover, the crystalplanes parallel to the above-described interface between theantiferromagnetic layer and the ferromagnetic layer are preferably thecrystallographically identical planes generically described as the {111}planes.

[0243] When the transmission electron beam diffraction diagramsdescribed above are obtained, it can be assumed that the crystal planesof the antiferromagnetic layer 4 and the pinned magnetic layer 3preferentially aligned parallel to the layer surface arecrystallographically identical and that particular crystallographicallyidentical crystal axes lying in these crystal planes of theantiferromagnetic layer 4 and the pinned magnetic layer 3 are orientedin different directions, at least partly.

[0244] In the spin-valve thin-film element shown in FIG. 3, the contentX or X+X′ constituting the antiferromagnetic layer 4 is preferably inthe range of 45 to 60 atomic percent. In this manner, an exchangecoupling magnetic field of 1.58×10⁴ (A/m) or more can be obtained.

[0245] More preferably, in the present invention, the content X or X+X′is in the range of 49 to 57 atomic percent. In this manner, an exchangecoupling magnetic field of 7.9×10⁴ (A/m) or more can be obtained.

[0246] As shown in FIG. 3, exchange bias layers (antiferromagneticlayers) 16 formed on the free magnetic layer 1 are separated in thetrack width direction (the X direction in the drawing) by a gapcorresponding to the track width Tw.

[0247] The exchange bias layers 16 comprise an X—Mn alloy wherein X isat least one element selected from the group consisting of Pt, Pd, Ir,Rh, Ru, and Os. More preferably, the exchange bias layers 16 comprise aPtMn alloy or an X—Mn—X′ alloy, wherein X′ is at least one elementselected from the group consisting of Ne, Ar, Kr, Xe, Be, B, C, N, Mg,Al, Si, P, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, Cd,Sn, Hf, Ta, W, Re, Au, Pb, and rare earth group elements.

[0248] In this embodiment, the crystal planes of the exchange biaslayers 16 and the free magnetic layer 1 preferentially aligned parallelto the layer surface are crystallographically identical, and that theparticular crystallographically identical crystal axes lying in thesecrystal planes of exchange bias layers 16 and the free magnetic layer 1are oriented in different directions, at least partly.

[0249] Moreover, in a cross-section of the exchange bias layers 16 andthe free magnetic layer 1 parallel to the layer thickness direction (theZ direction in the drawing), the crystal grain boundaries of theexchange bias layers 16 and those of the free magnetic layer 1 arediscontinuous at the interface, at least partly.

[0250] As a result, at least part of the above interface keeps thelattice-mismatching state, a proper order transformation can be achievedin the exchange bias layers 16 as a result of the heat treatment, and anincreased exchange coupling magnetic field can be obtained.

[0251] Preferably, the crystal planes of the exchange bias layers 16 andthe free magnetic layer 1 preferentially aligned parallel to the layersurface are the crystallographically identical planes genericallydescribed as the {111} planes. Preferably, the crystallographicallyidentical axes generically described as the <110> axes are oriented indifferent directions between the exchange bias layers 16 and the freemagnetic layer 1.

[0252] In the spin-valve thin-film element shown in FIG. 3, diffractionspots corresponding to the reciprocal lattice points indicative ofcrystal planes of the exchange bias layers 16 and the free magneticlayer 1 appear in transmission electron beam diffraction diagrams ofeach layer using an electron beam entering in a direction parallel tothe interface thereof. One diffraction spot which is given the samelabel and being located in the layer thickness direction when viewedfrom the beam origin is selected and a first imaginary line connectingthe diffraction spot and the beam origin is drawn for each of thediffraction diagrams. The first imaginary line in the diffractiondiagram of the exchange bias layers 16 and the first imaginary line inthe diffraction diagram of the free magnetic layer 1 are coincident witheach other.

[0253] Moreover, a second imaginary line in the diffraction diagram ofthe antiferromagnetic layer, connecting the beam origin and adiffraction spot indicative of a particular crystal plane and located ina direction other than the layer thickness direction when viewed fromthe beam origin, does not coincide with a second imaginary line drawn inthe same manner in the diffraction diagram of the ferromagnetic layer.In other cases, the diffraction spot indicative of a certain crystalplane and located in a direction other than the layer thicknessdirection appears in only one of the diffraction diagrams of theantiferromagnetic layer and ferromagnetic layer.

[0254] The diffraction spot located in the layer thickness direction ispreferably the one indicating one of the crystallographically identicalplanes generically described as the {111} planes.

[0255] Furthermore, in the spin-valve thin-film element shown in FIG. 3,diffraction spots corresponding to the reciprocal lattice pointsindicative of the crystal planes of the exchange bias layers 16 and thefree magnetic layer 1 appear in the transmission electron beamdiffraction diagrams obtained using an electron beam entering from adirection perpendicular to the interface between the above-describedinterface. Among the diffraction spots, one diffraction spot given thesame label in the diffraction diagrams of the exchange bias layers 16and the free magnetic layer 1 is selected and a imaginary lineconnecting the diffraction spot and the beam origin is drawn for each ofthe diffraction diagrams. The imaginary lines are not coincident witheach other at the diffraction diagrams of the exchange bias layers 16and the free magnetic layer 1. In other cases, the diffraction spotappears in only one of the diffraction diagrams of the exchange biaslayers 16 and the free magnetic layer 1.

[0256] Preferably, the direction perpendicular to the above-describedinterface is the direction of the crystallographically identical axesgenerically described as the <111> axes. Moreover, the crystal planespreferentially aligned parallel to the interface between theantiferromagnetic layer and the ferromagnetic layer are preferably thecrystallographically identical planes generically described as the {111}planes.

[0257] When a spin-valve thin-film element has the transmission electronbeam diagrams described above, it can be assumed that the crystal planesof the exchange bias layers 16 and the free magnetic layer 1preferentially aligned parallel to the layer surface arecrystallographically identical and that particular crystallographicallyidentical crystal axes lying in these crystal planes of the exchangebias layers 16 and the pinned free magnetic layer 1 are oriented indifferent directions, at least partly. Also, in the spin-valve thin-filmelement having the above-described transmission electron beamdiffraction images, a proper order transformation occurs in the exchangebias layers 16 as a result of heat treatment, and an increased couplingmagnetic field compared to the conventional technique can be obtained.

[0258] At the two side portions of the free magnetic layer 1, the freemagnetic layer 1 is put into a single domain state in the X direction inthe drawing by the exchange coupling magnetic field generated betweenthe exchange bias layers 16 and the free magnetic layer 1. The trackwidth (Tw) areas of the free magnetic layer 1 are adequately magnetizedin the X direction in the drawing to the extent that the area issensitive toward an external magnetic field.

[0259] In the single spin-valve magnetoresistive element having theabove configuration, the magnetization vector of the track width (Tw)areas of the free magnetic layer 1 changes from the X direction to the Ydirection in the drawing in response to an external magnetic fieldworking in the Y direction in the drawing. As the magnetization vectorin the free magnetic layer 1 is changed, the electrical resistance ischanged relative to the pinned magnetization vector (the Y direction inthe drawing) of the pinned magnetic layer 3. The change in electricalresistance leads to a change in voltage, and the leakage magnetic fieldfrom a recording medium is detected as the change in voltage.

[0260]FIG. 4 is a cross-sectional view showing part of the structure ofa spin-valve thin-film element according to a fourth embodiment of thepresent invention.

[0261] Referring to FIG. 4, a pair of seed layers 22 separated in thetrack width direction (the X direction in the drawing) by the gapcorresponding to the track width (Tw) is formed. Exchange bias layers 16are formed on the seed layers 22.

[0262] An insulation layer 17 comprising an insulating material such asSiO₂ or Al₂O₃ fills the gap between the seed layers 22 and the exchangebias layers 16.

[0263] A free magnetic layer 1 is formed on the exchange bias layers 16and the insulation layer 17.

[0264] The exchange bias layers 16 comprise an X—Mn alloy or an X—Mn—X′alloy. The content X or X+X′ is preferably in the range of 45 to 60atomic percent, and more preferably in the range of 49 to 56.5 atomicpercent.

[0265] A proper order transformation occurs in the exchange bias layers16 as a result of heat treatment without being restrained by the crystalstructure of the free magnetic layer 1. Consequently, an increasedexchange coupling magnetic field can be obtained compared to theconventional technology.

[0266] In this embodiment, the crystal planes of the exchange biaslayers 16 and the free magnetic layer 1 preferentially aligned parallelto the layer surface are crystallographically identical after the heattreatment. Particular crystal axes lying in these crystal planes ofexchange bias layers 16 and the free magnetic layer 1 are oriented indifferent directions, at least partly.

[0267] Moreover, in a cross-section of the exchange bias layers 16 andthe free magnetic layer 1 parallel to the layer thickness direction (theZ direction in the drawing), the crystal grain boundaries of theexchange bias layers 16 and those of the free magnetic layer 1 arediscontinuous at the interface, at least partly.

[0268] As a result, at least part of the above interface keeps thelattice-mismatching state, a proper order transformation can be achievedin the exchange bias layers 16 as a result of the heat treatment, and anincreased exchange coupling magnetic field can be obtained.

[0269] Preferably, the crystal planes of the exchange bias layers 16 andthe free magnetic layer 1 preferentially aligned parallel to the layersurface are the crystallographically identical planes genericallydescribed as the {111} planes. Preferably, the crystallographicallyidentical axes generically described as the <110> axes are oriented indifferent directions between the exchange bias layers 16 and the freemagnetic layer 1.

[0270] In the spin-valve thin-film element shown in FIG. 4, diffractionspots corresponding to the reciprocal lattice points indicative ofcrystal planes of the exchange bias layers 16 and the free magneticlayer 1 appear in transmission electron beam diffraction diagrams ofeach layer using an electron beam entering in a direction parallel tothe interface thereof. One diffraction spot which is given the samelabel and being located in the layer thickness direction when viewedfrom the beam origin is selected and a first imaginary line connectingthe diffraction spot and the beam origin is drawn for each of thediffraction diagrams. The first imaginary line in the diffractiondiagram of the exchange bias layers 16 and the first imaginary line inthe diffraction diagram of the free magnetic layer 1 are coincident witheach other.

[0271] Moreover, a second imaginary line in the diffraction diagram ofthe antiferromagnetic layer, connecting the beam origin and adiffraction spot indicative of a particular crystal plane and located ina direction other than the layer thickness direction when viewed fromthe beam origin does not coincide with a second imaginary line drawn inthe same manner in the diffraction diagram of the ferromagnetic layer.In other cases, the diffraction spot indicative of a certain crystalplane and located in a direction other than the layer thicknessdirection appears in only one of the diffraction diagrams of theantiferromagnetic layer and ferromagnetic layer.

[0272] The diffraction spot located in the layer thickness direction ispreferably the one indicating one of the crystallographically identicalplanes generically described as the {111} planes.

[0273] Furthermore, in the spin-valve thin-film element shown in FIG. 4,diffraction spots corresponding to the reciprocal lattice pointsindicative of the crystal planes of the exchange bias layers 16 and thefree magnetic layer 1 appear in the transmission electron beamdiffraction diagrams obtained using an electron beam entering from adirection perpendicular to the interface between the above-describedinterface. Among the diffraction spots, one diffraction spot given thesame label in the diffraction diagrams of the exchange bias layers 16and the free magnetic layer 1 is selected and a imaginary lineconnecting the diffraction spot and the beam origin is drawn for each ofthe diffraction diagrams. The imaginary lines are not coincident witheach other at the diffraction diagrams of the exchange bias layers 16and the free magnetic layer 1. In other cases, the diffraction spotappears in only one of the diffraction diagrams of the exchange biaslayers 16 and the free magnetic layer 1.

[0274] Preferably, the direction perpendicular to the above-describedinterface is the direction of the crystallographically identical axesgenerically described as the <111> axes. Moreover, the crystal planespreferentially aligned parallel to the interface between theantiferromagnetic layer and the ferromagnetic layer are preferably thecrystallographically identical planes generically described as the {111}planes.

[0275] When the transmission electron beam diagrams as described aboveare obtained, it can be assumed that the crystal planes of the exchangebias layers 16 and the free magnetic layer 1 preferentially alignedparallel to the layer surface are crystallographically identical andthat particular crystallographically identical crystal axes lying inthese crystal planes of the exchange bias layers 16 and the freemagnetic layer 1 are oriented in different directions, at least partly.Also, in the spin-valve thin-film element having the above-describedtransmission electron beam diffraction images, a proper ordertransformation occurs in the exchange bias layers 16 as a result of heattreatment, and an increased coupling magnetic field compared to theconventional technique can be obtained.

[0276] At the two side portions of the free magnetic layer 1, the freemagnetic layer 1 is put into a single domain state in the X direction inthe drawing by the exchange coupling magnetic field generated betweenthe exchange bias layers 16 and the free magnetic layer 1. The trackwidth (Tw) areas of the free magnetic layer 1 are adequately magnetizedin the X direction in the drawing to the extent that the area issensitive toward an external magnetic field.

[0277] Referring to FIG. 4, a nonmagnetic interlayer 2 is formed on thefree magnetic layer 1. A pinned magnetic layer 3 is formed on thenonmagnetic interlayer 2. An antiferromagnetic layer 4 is formed on thepinned magnetic layer 3.

[0278] In this embodiment, the crystal planes of the antiferromagneticlayer 4 and the pinned magnetic layer 3 preferentially aligned parallelto the layer surface are crystallographically identical after the heattreatment. Also, particular crystallographically identical crystal axeslying in these crystal planes of the antiferromagnetic layer 4 and thepinned magnetic layer 3 are oriented in different directions, at leastpartly.

[0279] In a cross section of the antiferromagnetic layer 4 and thepinned magnetic layer 3 parallel to the layer thickness direction (the Zdirection in the drawing), the crystal grain boundaries of theantiferromagnetic layer 4 and those of the pinned magnetic layer 3 arediscontinuous at the interface, at least partly.

[0280] As a result, at least part of the above interface keeps thelattice-mismatching state, a proper order transformation can be achievedin the antiferromagnetic layer 4 as a result of the heat treatment, andan increased exchange coupling magnetic field can be obtained.

[0281] Preferably, the crystal planes of the antiferromagnetic layer 4and the pinned magnetic layer 3 preferentially aligned parallel to thelayer surface are the crystallographically identical planes genericallydescribed as the {111} planes. Preferably, the crystallographicallyidentical axes generically described as the <110> axes are oriented indifferent directions between the antiferromagnetic layer 4 and thepinned magnetic layer 3.

[0282] In the spin-valve thin-film element shown in FIG. 4, diffractionspots corresponding to the reciprocal lattice points indicative ofcrystal planes of the antiferromagnetic layer 4 and the pinned magneticlayer 3 appear in transmission electron beam diffraction diagrams of theantiferromagnetic layer 4 and the pinned magnetic layer 3 using anelectron beam entering in a direction parallel to the interface thereof.One diffraction spot which is given the same label and being located inthe layer thickness direction when viewed from the beam origin isselected and a first imaginary line connecting the diffraction spot andthe beam origin is drawn for each of the diffraction diagrams. The firstimaginary line in the diffraction diagram of the pinned magnetic layer 3and the first imaginary line in the diffraction diagram of theantiferromagnetic layer 4 are coincident with each other.

[0283] Moreover, a second imaginary line in the diffraction diagram ofthe antiferromagnetic layer 4, connecting the beam origin and adiffraction spot indicative of a particular crystal plane and located ina direction other than the layer thickness direction when viewed fromthe beam origin does not coincide with a second imaginary line drawn inthe same manner in the diffraction diagram of the pinned magnetic layer3. In other cases, the diffraction spot indicative of a certain crystalplane and located in a direction other than the layer thicknessdirection appears in only one of the diffraction diagrams of theantiferromagnetic layer and ferromagnetic layer.

[0284] The diffraction spot located in the layer thickness direction ispreferably the one indicating one of the crystallographically identicalplanes generically described as the {111} planes.

[0285] Furthermore, in the spin-valve thin-film element shown in FIG. 4,diffraction spots corresponding to the reciprocal lattice pointsindicative of the crystal planes of the pinned magnetic layer 3 and theantiferromagnetic layer 4 appear in the transmission electron beamdiffraction diagrams obtained using an electron beam entering from adirection perpendicular to the interface between the antiferromagneticlayer 4 and the pinned magnetic layer 3. Among the diffraction spots,one diffraction spot given the same label in the diffraction diagrams ofthe pinned magnetic layer 3 and the antiferromagnetic layer 4 isselected and a imaginary line connecting the diffraction spot and thebeam origin is drawn for each of the diffraction diagrams. The imaginarylines are not coincident with each other at the diffraction diagrams ofthe pinned magnetic layer 3 and that of the antiferromagnetic layer 4.In other cases, the diffraction spot appears in only one of thediffraction diagrams of the antiferromagnetic layer 4 and the pinnedmagnetic layer 3.

[0286] Preferably, the direction perpendicular to the above-describedinterface is the direction of the crystallographically identical axesgenerically described as the <111> axes. Moreover, the crystal planespreferentially aligned parallel to the interface between theantiferromagnetic layer and the ferromagnetic layer are preferably thecrystallographically identical planes generically described as the {111}planes.

[0287] When the transmission electron beam diagrams as described aboveare obtained, it can be assumed that the crystal planes of theantiferromagnetic layer 4 and the pinned magnetic layer 3 preferentiallyaligned parallel to the layer surface are crystallographicallyidentical, and that the particular crystallographically identicalcrystal axes lying in these crystal planes of the antiferromagneticlayer 4 and the pinned magnetic layer 3 are oriented in differentdirections, at least partly. Also, in the spin-valve thin-film elementhaving the above-described transmission electron beam diffractionimages, a proper order transformation occurs in the antiferromagneticlayer 4 as a result of heat treatment, and an increased couplingmagnetic field compared to the conventional technique can be obtained.

[0288]FIG. 5 is a cross-sectional view showing part of the structure ofa dual spin-valve thin-film element according to still another aspect ofthe present invention.

[0289] Referring to FIG. 5, the dual spin-valve thin-film elementcomprises an underlayer 6, a seed layer 22, an antiferromagnetic layer4, a pinned magnetic layer 3, a nonmagnetic interlayer 2, and a freemagnetic layer 1, deposited in that order from the bottom. The freemagnetic layer 1 comprises three layers, namely, Co layers 10 and a NiFealloy layer 9. A nonmagnetic interlayer 2, a pinned magnetic layer 3, anantiferromagnetic layer 4, and a protective layer 7 are deposited on thefree magnetic layer

[0290] Hard bias layers 5 and conductive layers 8 are deposited on twosides of the layers from the underlayer 6 to the protective layer 7.Each layers are composed of the same material as in the first embodimentshown in FIG. 1.

[0291] In this embodiment, the seed layer 22 is provided under the underthe antiferromagnetic layer 4 located below the free magnetic layer 1 inthe drawing. The content X or X+X′ constituting the antiferromagneticlayer 4 is preferably in the range of 45 to 60 atomic percent, and morepreferably in the range of 49 to 56.5 atomic percent.

[0292] In this embodiment, the crystal planes of the antiferromagneticlayer 4 and the pinned magnetic layer 3 preferentially aligned parallelto the layer surface are crystallographically identical, and that theparticular crystallographically identical crystal axes lying in thesecrystal planes of the antiferromagnetic layer 4 and the pinned magneticlayer 3 are oriented in different directions, at least partly.

[0293] Moreover, in a cross-section of the antiferromagnetic layer 4 andthe pinned magnetic layer 3 parallel to the layer thickness direction(the Z direction in the drawing), the crystal grain boundaries of theantiferromagnetic layer 4 and those of the pinned magnetic layer 3 arediscontinuous at the interface, at least partly.

[0294] As a result, at least part of the interface keeps thelattice-mismatching state. A proper order transformation occurs in theantiferromagnetic layer 4 as a result of heat treatment and a strongexchange coupling magnetic field can be obtained.

[0295] Preferably, the crystal planes of the antiferromagnetic layer 4and the pinned magnetic layer 3 preferentially aligned parallel to thelayer surface are the crystallographically identical planes genericallydescribed as the {111} planes. Preferably, the crystallographicallyidentical axes generically described as the <110> axes are oriented indifferent directions between the antiferromagnetic layer 4 and thepinned magnetic layer 3.

[0296] In the dual spin-valve thin-film element of this embodiment shownin FIG. 5, not only the pinned magnetic layer 3 and theantiferromagnetic layer 4 provided below the free magnetic layer 1, buteach of the deposited layers has the above-described crystalorientation.

[0297] That is, in this embodiment, the crystal planes of theantiferromagnetic layer 4 and the pinned magnetic layer 3 preferentiallyaligned parallel to the layer surface are crystallographicallyidentical, and that the particular crystallographically identicalcrystal axes lying in these crystal planes of the antiferromagneticlayer 4 and the pinned magnetic layer 3 are oriented in differentdirections, at least partly.

[0298] Moreover, in a cross-section of the antiferromagnetic layer 4 andthe pinned magnetic layer 3 parallel to the layer thickness direction(the Z direction in the drawing), the crystal grain boundaries of theantiferromagnetic layer 4 and those of the pinned magnetic layer 3 arediscontinuous at the interface, at least partly.

[0299] As a result, at least part of the above interface keeps thelattice-mismatching state, a proper order transformation can be achievedin the antiferromagnetic layer 4 as a result of the heat treatment, andan increased exchange coupling magnetic field can be obtained.

[0300] Preferably, the crystal planes of the antiferromagnetic layer 4and the pinned magnetic layer 3 preferentially aligned parallel to thelayer surface are the crystallographically identical planes genericallydescribed as the {111} planes. Preferably, the crystallographicallyidentical axes generically described as the <110> axes are oriented indifferent directions between the antiferromagnetic layer 4 and thepinned magnetic layer 3.

[0301] In the spin-valve thin-film element shown in FIG. 5, diffractionspots corresponding to the reciprocal lattice points indicative ofcrystal planes of the antiferromagnetic layer 4 and the pinned magneticlayer 3 appear in transmission electron beam diffraction diagrams of theantiferromagnetic layer 4 and the pinned magnetic layer 3 using anelectron beam entering in a direction parallel to the interface thereof.One diffraction spot which is given the same label and being located inthe layer thickness direction when viewed from the beam origin isselected and a first imaginary line connecting the diffraction spot andthe beam origin is drawn for each of the diffraction diagrams. The firstimaginary line in the diffraction diagram of the pinned magnetic layer 3and the first imaginary line in the diffraction diagram of theantiferromagnetic layer 4 are coincident with each other.

[0302] Moreover, a second imaginary line in the diffraction diagram ofthe antiferromagnetic layer 4, connecting the beam origin and adiffraction spot indicative of a particular crystal plane and located ina direction other than the layer thickness direction when viewed fromthe beam origin does not coincide with a second imaginary line drawn inthe same manner in the diffraction diagram of the pinned magnetic layer3. In other cases, the diffraction spot indicative of a certain crystalplane and located in a direction other than the layer thicknessdirection appears in only one of the diffraction diagrams of theantiferromagnetic layer and ferromagnetic layer.

[0303] The diffraction spot located in the layer thickness direction ispreferably the one indicating one of the crystallographically identicalplanes generically described as the {111} planes.

[0304] Furthermore, in the spin-valve thin-film element shown in FIG. 5,diffraction spots corresponding to the reciprocal lattice pointsindicative of the crystal planes of the pinned magnetic layer 3 and theantiferromagnetic layer 4 appear in the transmission electron beamdiffraction diagrams obtained using an electron beam entering from adirection perpendicular to the interface between the antiferromagneticlayer 4 and the pinned magnetic layer 3. Among the diffraction spots,one diffraction spot given the same label in the diffraction diagrams ofthe pinned magnetic layer 3 and the antiferromagnetic layer 4 isselected and a imaginary line connecting the diffraction spot and thebeam origin is drawn for each of the diffraction diagrams. The imaginarylines are not coincident with each other at the diffraction diagrams ofthe pinned magnetic layer 3 and that of the antiferromagnetic layer 4.In other cases, the diffraction spot appears in only one of thediffraction diagrams of the antiferromagnetic layer 4 and the pinnedmagnetic layer 3.

[0305] Preferably, the direction perpendicular to the above-describedinterface is the direction of the crystallographically identical axesgenerically described as the <111> axes. Moreover, the crystal planespreferentially aligned parallel to the interface between theantiferromagnetic layer and the ferromagnetic layer are preferably thecrystallographically identical planes generically described as the {111}planes.

[0306] When the transmission electron beam diagrams as described aboveare obtained, it can be assumed that the crystal planes of theantiferromagnetic layer 4 and the pinned magnetic layer 3 preferentiallyaligned parallel to the layer surface are crystallographicallyidentical, and that the particular crystallographically identicalcrystal axes lying in these crystal planes of the antiferromagneticlayer 4 and the pinned magnetic layer 3 are oriented in differentdirections, at least partly. Also, in the spin-valve thin-film elementhaving the above-described transmission electron beam diffractionimages, a proper order transformation occurs in the antiferromagneticlayer 4 as a result of heat treatment, and an increased couplingmagnetic field compared to the conventional technique can be obtained.

[0307]FIG. 6 is a cross-sectional view illustrating the structure of anAMR magnetoresistive element according to a sixth embodiment of thepresent invention.

[0308] The AMR magnetoresistive element comprises a soft magnetic layer(SAL) 18, a nonmagnetic layer (shunt layer) 19, and a magnetoresistivelayer 20, deposited in that order from the bottom.

[0309] For example, the soft magnetic layer 18 comprises an Fe—Ni—Nballoy, the nonmagnetic layer 19 comprises tantalum (Ta), and themagnetoresistive layer 20 comprises a NiFe alloy.

[0310] Exchange bias layers (antiferromagnetic layers) 21, separatedfrom one another in a track width direction (the X direction in thedrawing) with a gap corresponding to the track width Tw therebetween,are formed on the two side portions of the magnetoresistive layer 20.Conductive layers (not shown in the drawing) are formed, for example, onthe exchange bias layers 21.

[0311]FIG. 7 is a cross-sectional view illustrating the structure of anAMR magnetoresistive element according to a seventh embodiment of thepresent invention.

[0312] Referring to FIG. 7, a pair of seed layers 22 is formed separatedfrom one another in the track width direction (the X direction in thedrawing) with a gap corresponding to a track width Tw therebetween.Exchange bias layers 21 are formed on the seed layers 22. The gapbetween the seed layers 22 provided with the exchange bias layers 21thereon is filled with an insulative material such as SiO₂ or Al₂O₃ soas to form an insulation layer 26.

[0313] A magnetoresistive layer (MR layer) 20, a nonmagnetic layer(shunt layer) 19, and a soft magnetic layer (SAL layer) are deposited onthe exchange bias layers 21 and the insulation layer 26.

[0314] In the embodiments shown in FIGS. 6 and 7, the crystal planes ofthe exchange bias layers 21 and the magnetoresistive layer 20preferentially aligned parallel to the layer surface arecrystallographically identical, and particular crystallographicallyidentical crystal axes lying in these crystal planes of the exchangebias layers 21 and the magnetoresistive layer 20 are oriented indifferent directions, at least partly.

[0315] Moreover, in a cross-section of the exchange bias layers 21 andthe magnetoresistive layer 20 parallel to the layer thickness direction(the Z direction in the drawing), the crystal grain boundaries of theexchange bias layers 21 and those of the magnetoresistive layer 20 arediscontinuous at the interface, at least partly.

[0316] As a result, at least part of the above interface keeps thelattice-mismatching state, a proper order transformation can be achievedin the exchange bias layers 21 as a result of the heat treatment, and anincreased exchange coupling magnetic field can be obtained.

[0317] Preferably, the crystal planes of the exchange bias layers 21 andthe magnetoresistive layer 20 preferentially aligned parallel to thelayer surface are the crystallographically identical planes genericallydescribed as the {111} planes. Preferably, the crystallographicallyidentical axes generically described as the <110> axes are oriented indifferent directions between the exchange bias layers 21 and themagnetoresistive layer 20.

[0318] In the AMR thin-film elements shown in FIGS. 6 and 7, diffractionspots corresponding to the reciprocal lattice points indicative ofcrystal planes of the exchange bias layers 21 and the magnetoresistivelayer 20 appear in transmission electron beam diffraction diagrams ofthe exchange bias layers 21 and the magnetoresistive layer 20 using anelectron beam entering in a direction parallel to the interface thereof.One diffraction spot which is given the same label and being located inthe layer thickness direction when viewed from the beam origin isselected and a first imaginary line connecting the diffraction spot andthe beam origin is drawn for each of the diffraction diagrams. The firstimaginary line in the diffraction diagram of the antiferromagnetic layerand the first imaginary line in the diffraction diagram of theferromagnetic layer are coincident with each other.

[0319] Moreover, a second imaginary line in the diffraction diagram ofthe antiferromagnetic layer, the line connecting the beam origin and adiffraction spot indicative of a particular crystal plane and located ina direction other than the layer thickness direction when viewed fromthe beam origin, does not coincide with a second imaginary line drawn inthe same manner in the diffraction diagram of the ferromagnetic layer.In other cases, the diffraction spot indicative of a certain crystalplane and located in a direction other than the layer thicknessdirection appears in only one of the diffraction diagrams of theantiferromagnetic layer and ferromagnetic layer.

[0320] The diffraction spot located in the layer thickness direction ispreferably the one indicating one of the crystallographically identicalplanes generically described as the {111} planes.

[0321] Furthermore, in the AMR thin-film elements shown in FIGS. 6 and7, diffraction spots corresponding to the reciprocal lattice pointsindicative of the crystal planes of the exchange bias layers 21 and themagnetoresistive layer 20 appear in the transmission electron beamdiffraction diagrams obtained using an electron beam entering from adirection perpendicular to the above-described interface. Among thediffraction spots, one diffraction spot given the same label in thediffraction diagrams of exchange bias layers 21 and the magnetoresistivelayer 20 is selected and a imaginary line connecting the diffractionspot and the beam origin is drawn for each of the diffraction diagrams.The imaginary lines are not coincident with each other at thediffraction diagrams of the exchange bias layers 21 and that of themagnetoresistive layer 20. In other cases, the diffraction spot appearsin only one of the diffraction diagrams of the exchange bias layers 21and the magnetoresistive layer 20.

[0322] Preferably, the direction perpendicular to the above-describedinterface is the direction of the crystallographically identical axesgenerically described as the <111> axes. Moreover, the crystal planespreferentially aligned parallel to the interface between theantiferromagnetic layer and the ferromagnetic layer are preferably thecrystallographically identical planes generically described as the {111}planes.

[0323] When the transmission electron beam diagrams as described aboveare obtained, it can be assumed that the crystal planes of the exchangebias layers 21 and the magnetoresistive layer 20 preferentially alignedparallel to the layer surface are crystallographically identical, andthat the particular crystallographically identical crystal axes lying inthese crystal planes of the exchange bias layers 21 and themagnetoresistive layer 20 are oriented in different directions, at leastpartly. Moreover, a proper order transformation occurs in the exchangebias layers 21 as a result of heat treatment, and an increased couplingmagnetic field compared to the conventional technique can be obtained.

[0324] In each of the AMR thin-film elements shown in FIGS. 6 and 7, anexchange coupling magnetic field generated at the interface between theexchange bias layers 21 and the magnetoresistive layer 20 puts the areasE of the magnetoresistive layer 20 into a single-domain state in the Xdirection in the drawings. As a result, the magnetization vector in thearea D of the magnetoresistive layer 20 is oriented in the X directionin the drawings. The galvanomagnetism generated when sense current flowsinto the magnetoresistive layer 20 is applied to the soft magnetic layer18 in the Y direction in the drawings. By the magnetostatic couplingenergy yielded by the soft magnetic layer 18, a lateral bias magneticfield is applied to the area D of the magnetoresistive layer 20 in the Ydirection. When the lateral bias magnetic field is applied to the D areaof the magnetoresistive layer 20 being put into a single-domain state inthe X direction, the area D of the magnetoresistive layer 20 achieves alinear change in resistance in response to changes in magnetic fields(magnetoresistive characteristics: H-R characteristics).

[0325] A recording medium moves in the Z direction in the drawing. Whena leakage magnetic field is applied in the Y direction in the drawing,the resistance in the D area of the magnetoresistive layer 20 changesand this change is detected as the change in voltage.

[0326] Regarding the method for making the magnetoresistive elementsshown in FIGS. 1 to 7, the antiferromagnetic layer 4 thereof ispreferably made as follows.

[0327] As described earlier, the content of X or total content of X andX′ in the antiferromagnetic layer 4 is preferably in the range of 45 to60 atomic percent, and more preferably in the range of 49 to 56.5 atomicpercent. In this manner, an increased exchange coupling magnetic fieldcan be achieved as shown in the experimental results described below.

[0328] Accordingly, one method for making the magnetoresistive head ofthe present invention comprises depositing the antiferromagnetic layer 4of the above composition, depositing the rest of the layers, andperforming a thermal treatment.

[0329] Each of the interface between the antiferromagnetic layer 4 andthe pinned magnetic layer 3, the interface between the exchange biaslayers 16 and the free magnetic layer 1, the interface between exchangebias layers 21 and the magnetoresistive layer 20, the interface betweenthe seed layer 22 and the antiferromagnetic layer 4 in case the seedlayer 22 is formed, is preferably in a lattice-mismatching state atleast partly subsequent to the thermal treatment. Thelattice-mismatching state is preferably achieved during the layerdeposition step. When these interfaces are in a lattice-matching stateduring the deposition step, the antiferromagnetic layer 4 does notproperly transform into an ordered lattice even after the thermaltreatment.

[0330] In order to keep these interfaces in a lattice-mismatching stateduring the deposition step, it is preferable that the antiferromagneticlayer 4 and other layers be deposited as follows.

[0331]FIG. 8 illustrates the layers in as-deposited state. The layerscorrespond to those in FIG. 1. As shown in FIG. 8, after the underlayeris deposited on a seed layer 22, an antiferromagnetic layer 4 comprisingthree layers is deposited. A first antiferromagnetic layer 23, a secondantiferromagnetic layer 24, and a third antiferromagnetic layer 25 whichconstitute the antiferromagnetic layer 4 are formed of an X—Mn alloy oran X—Mn—X′ alloy.

[0332] During the step of deposition, the content X or X+X′ in the firstantiferromagnetic layer 23 and the third antiferromagnetic layer 25 isset larger than the content X or X+X′ contained in the secondantiferromagnetic layer 24.

[0333] The second antiferromagnetic layer 24 formed between the firstantiferromagnetic layer 23 and the third antiferromagnetic layer 25 isformed of an antiferromagnetic material of the type most suitable foryielding transformations from a disordered lattice to a ordered latticeas a result of heat treatment.

[0334] When the content of X or X +X′ contained in the firstantiferromagnetic layer 23 and the third antiferromagnetic layer 25 isset larger than the content X or X+X′ contained in the secondantiferromagnetic layer 24, the disordered lattice of theantiferromagnetic layer 4 readily transforms into an ordered latticethrough a thermal treatment. This is because, the antiferromagneticlayer is not restrained by the crystal structure, etc., of the pinnedmagnetic layer 3 or the seed layer 22.

[0335] The content X or the total content of X and X′ in the firstantiferromagnetic layer 23 and the third antiferromagnetic layer 25 ispreferably in the range of 53 to 65 atomic percent, and more preferablyin the range of 55 t 60 atomic percent. The thickness of the firstantiferromagnetic layer 23 and the third antiferromagnetic layer 25 ispreferably in the range of 3 to 30 angstroms, respectively. For example,in FIG. 8, the thickness of the first and third antiferromagnetic layers23 and 25 is approximately 10 angstroms.

[0336] The content X or the total content of X and X′ in the secondantiferromagnetic layer 24 is in the range of 44 to 57 atomic percent,preferably in the range of 46 to 55 atomic percent. In this manner, thedisorder lattice of the second antiferromagnetic layer 24 is readilytransformed in to an ordered lattice as a result of heat treatment. Thethickness of the second antiferromagnetic layer 24 is preferably 70angstroms or more. In the embodiment shown in FIG. 8, the thickness ofthe second antiferromagnetic layer 24 is approximately 100 angstroms.

[0337] The first, second, and third antiferromagnetic layers 23, 24, and25 are preferably made by a sputtering method. It is preferable that thepressure of the sputter gas used in making the first antiferromagneticlayer 23 and the third antiferromagnetic layer 25 be lower than thatused in making the second antiferromagnetic layer 24. In this manner,The content X or the total content of X and X′ in the secondantiferromagnetic layer 24 and the third antiferromagnetic layer 25 canbe made larger than that of the second antiferromagnetic layer 24.

[0338] Alternatively, the antiferromagnetic layer 4 in as-depositedstate (before heat treatment) can be formed of one layer instead ofthree layers as described above. In this case, it is also possible toproperly change the content of X or X+X′ along the layer thicknessdirection by the process described below.

[0339] First, in the course of making the antiferromagnetic layer 4 bysputtering using a target formed of an antiferromagnetic materialcontaining X and Mn or X′, X′, and Mn, the pressure of the sputter gasis gradually elevated as the deposition proceeds. Once approximately onehalf of the antiferromagnetic layer 4 is deposited, the pressure of thesputter gas is gradually reduced so as to deposit the rest of theantiferromagnetic layer 4.

[0340] In this manner, the content of X or X+X′ is gradually decreasedfrom the interface with the seed layer 22 toward the center portion ofthe antiferromagnetic layer 4 in the layer thickness direction and isgradually increased from the center portion toward the interface withthe pinned magnetic layer 3.

[0341] Accordingly, the content of X or X+X′ in the antiferromagneticlayer 4 is high at the interfaces between the antiferromagnetic layer 4and the seed layer 22, and between the antiferromagnetic layer 4 and thepinned magnetic layer 3, and is low at the center portion of theantiferromagnetic layer 4 in layer thickness direction.

[0342] Preferably, in the portions contacting the pinned magnetic layer3 and the interface between the seed layer 22, the X or X+X′ content inthe antiferromagnetic layer 4 is in the range of 53 to 65 atomicpercent, and more preferably in the range of 55 to 60 atomic percent ofthe all elements constituting the antiferromagnetic layer 4.

[0343] Preferably, in the center portion of the antiferromagnetic layer4 in the layer thickness direction, the X or X+X′ content is in therange of 44 to 57 atomic percent, and more preferably in the range of 46to 55 atomic percent. The thickness of the antiferromagnetic layer 4 ispreferably 76 angstroms or more.

[0344]FIG. 9 is a illustration of the spin-valve thin-film elementshowing the state of the layers after the heat treatment.

[0345] Here, the first antiferromagnetic layer 23 and the thirdantiferromagnetic layer 25 having a higher X or X+X′ content are incontact with the pinned magnetic layer and the seed layer 22, and thesecond antiferromagnetic layer 24 having a composition readilytransformable from an disordered lattice to an ordered lattice throughheat treatment is provided between the first antiferromagnetic layer 23and the third antiferromagnetic layer 25. During the heat treatment, thetransformation proceeds in the second antiferromagnetic layer 24 whilediffusion of elements occurs at the interfaces between the secondantiferromagnetic layer 24 and the first antiferromagnetic layer 23, andbetween the second antiferromagnetic layer 24 and the thirdantiferromagnetic layer 25. As a result, a desirable lattice-mismatchingstate can be maintained at the interfaces between the firstantiferromagnetic layer 23 and the pinned magnetic layer 3, and betweenthe third antiferromagnetic layer 25 and the seed layer 22, thedisordered lattice is transformed into an ordered lattice, and theentire antiferromagnetic layer 4 can be properly transformed into anordered lattice structure.

[0346] In the spin-valve thin-film element after the heat treatment, thesame crystallographically identical crystal planes are preferentiallyoriented parallel to the layer surface at the antiferromagnetic layer 4and the pinned magnetic layer 3. Moreover, the same crystallographicallyidentical crystal axes lying in the above-described planes are orientedin different directions between the antiferromagnetic layer 4 and thepinned magnetic layer 3, at least partly.

[0347] When a cross section of the antiferromagnetic layer 4 and thepinned magnetic layer 3 cut parallel to the layer thickness direction(the Z direction in the drawing) is examined, the crystal grainboundaries of the antiferromagnetic layer 4 and those of the pinnedmagnetic layer 3 are discontinuous at the interface thereof, at leastpartly.

[0348] It should be noted that in the antiferromagnetic layer 4 afterthe heat treatment, there are regions towards the seed layer 22 and thepinned magnetic layer 3 having an increased X or X+X′ content relativeto Mn.

[0349] In the case of making the spin-valve thin-film element shown inFIG. 2, the antiferromagnetic layer 4 may alternatively be composed oftwo layers, namely, the first antiferromagnetic layer 23 in contact withthe pinned magnetic layer 3 and the second antiferromagnetic layer 24 incontact with the protective layer 7, instead of three layers asdescribed above. This is allowable because in this spin-valve thin-filmelement, the seed layer 22 is not provided as in the first embodiment ofFIG. 1.

[0350] When the antiferromagnetic layer 4 is composed of two layers, thecontent X or X+X′ relative to Mn is gradually increased towards theinterface with the pinned magnetic layer 3.

[0351] In the spin-valve thin-film element of FIG. 3, each of theexchange bias layers 16 is formed as two layers as in the case of FIG.2. The first antiferromagnetic layer 23 is put into contact with thefree magnetic layer 1. The second antiferromagnetic layer 24 is formedso as not to contact the free magnetic layer 1.

[0352] The antiferromagnetic layer 4 of the spin-valve thin-film elementin FIG. 3 is formed as three layers as in the case of the element inFIG. 1. Through thermal treatment, a proper transformation occurs in theexchange bias layers 16 and the antiferromagnetic layer 4, and anincreased exchange coupling magnetic field can be generated.

[0353] In the exchange bias layer 16 after the heat treatment, there isa region with an increased X or X+X′ content in terms atomic percentrelative to Mn towards the free magnetic layer 1.

[0354] In the antiferromagnetic layer 4 after the heat treatment, thereare regions with an increased X or X+X′ content in terms of atomicpercent relative to Mn towards the pinned magnetic layer 3 and the seedlayer 22.

[0355] Regarding a method for manufacturing the spin-valve thin-filmelement shown in FIG. 4, the antiferromagnetic layer 4 is formed as twolayers as in FIG. 2. The first antiferromagnetic layer 23 is provided incontact with the pinned magnetic layer 3 and the 24 is formed so as notto contact the pinned magnetic layer 3.

[0356] Each of the exchange bias layers 16 are formed as three layers asin the antiferromagnetic layer 4 of the FIG. 1. Through the thermaltreatment, a proper order transformation occurs at the exchange biaslayers 16 and the antiferromagnetic layer 4, and an increased exchangecoupling magnetic field can be generated.

[0357] In each of the exchange bias layers 16 after the heat treatment,there are regions with an increased X or X+X′ content in terms of atomicpercent relative to Mn towards the free magnetic 1 and the seed layer22.

[0358] In the antiferromagnetic layer 4 after the heat treatment, thereis a region with an increased X or X+X′ content in terms of atomicpercent relative to Mn towards the pinned magnetic layer 3.

[0359] Regarding a method for making the dual spin-valve thin-filmelement shown in FIG. 5, the antiferromagnetic layer 4 disposed belowthe free magnetic layer 1 is formed as three layers, namely, the firstantiferromagnetic layer 23 and the second antiferromagnetic layer 24,and the third antiferromagnetic layer 25. The antiferromagnetic layer 4disposed above the free magnetic layer 1 is formed as two layers,namely, a first antiferromagnetic layer 14 and a secondantiferromagnetic layer 15.

[0360] The thickness and the composition of each of the firstantiferromagnetic layers 14 and 23 and the second antiferromagneticlayers 24, and the third antiferromagnetic layer 25 are the same as thedescription made regarding to FIG. 1.

[0361] After the layers are deposited as in FIG. 10, a heat treatment isperformed. The layers after the heat treatment are shown in FIG. 11. InFIG. 11, diffusion of elements occurs among the three layersconstituting the antiferromagnetic layer 4, and there are regions havingan increased X or X+X′ content in terms of atomic percent relative to Mntowards the pinned magnetic layer 3 and the seed layer 22.

[0362] Diffusion of elements also occurs between the two layersconstituting the antiferromagnetic layer 4 formed above the freemagnetic layer 1. In the antiferromagnetic layer 4 after the heattreatment, there is a region with an increased X or X+X′ content interms of atomic percent relative to Mn toward the pinned magnetic layer3.

[0363] Regarding a method for making the AMR thin-film element shown inFIG. 6, each of the exchange bias layers 21 is formed as two layers asin the antiferromagnetic layer 4 located above the free magnetic layer 1shown in FIG. 10. Each of the exchange bias layers 21 comprises thefirst antiferromagnetic layer 14 in contact with a magnetoresistivelayer 20, and the second antiferromagnetic layer 15 is formed so as notto contact the magnetoresistive layer 20.

[0364] In the course of the heat treatment, a proper ordertransformation occurs in the exchange bias layers 21, thereby generatingan increased exchange coupling magnetic field at the interfaces betweenthe magnetoresistive layer 20 and the exchange bias layers 21.

[0365] In each of the exchange bias layers 21 after the heat treatment,there is a region having an increased X or X+X′ content in terms atomicpercent,relative to Mn towards the magnetoresistive layer 20.

[0366] Regarding a method for making the AMR thin-film element shown inFIG. 7, each of the exchange bias layers 21 is composed of three layersas in the antiferromagnetic layer 4 shown in FIG. 8. The exchange biaslayer 21 comprises the first antiferromagnetic layer 23 in contact withthe magnetoresistive layer 20, the third antiferromagnetic layer 25 incontact with the seed layer 22, and the second antiferromagnetic layer24 provided between the first antiferromagnetic layer 23 and the thirdantiferromagnetic layer 25.

[0367] Through the heat treatment, a proper order transformation occursin the exchange bias layers 21, and an increased exchange couplingmagnetic field is generated between the magnetoresistive layer 20 andthe exchange bias layers 21.

[0368] In the exchange bias layer 21 after the heat treatment, there areregions with an increased X or X+X′ content in terms of atomic percentrelative to Mn towards the magnetoresistive layer 20 and the seed layer22.

[0369]FIG. 12 is a cross-section showing the structure of a read headincorporating one of the magnetoresistive elements shown in FIGS. 1 to11 as viewed from the side facing a recording medium.

[0370] The bottom most layer in the drawing is a lower shield layer 40comprising a NiFe alloy or the like. A lower gap layer 41 is formed onthe lower shield layer 40. A magnetoresistive element 42 according toone of FIGS. 1 to 7 is provided on the lower gap layer 41. An upper gaplayer 43 is provided on the magnetoresistive element 42, and an uppershield layer 44 comprising a NiFe alloy or the like is provided on theupper gap layer 43.

[0371] The lower gap layer 41 and the upper gap layer 43 are composed ofan insulative material such as SiO₂, Al₂O₃ (alumina) or the like. Asshown in FIG. 12, a gap length (Gl) is defined as the length from thelower surface of the lower gap layer 41 to the upper surface of theupper gap layer 43. The element having a smaller gap length Gl iscapable of meeting the demand for higher recording density.

[0372] According to the present invention, an increased exchangecoupling magnetic field can still be generated even when the thicknessof the antiferromagnetic layer 4 is reduced. As a result, the thicknessof the magnetoresistive element can be reduced compared to theconventional ones and it becomes possible to manufacture thin-filmmagnetic heads having a reduced gap length capable of meeting the demandfor higher recording density.

[0373] Although the antiferromagnetic layer 4, the exchange bias layers16, and the magnetoresistive layer 20 shown in FIGS. 1, 3, 4, 5, and 7are respectively provided with the seed layer 22 thereunder, the scopeof the invention is not limited to these.

[0374] Moreover, when the crystal grain boundaries of theantiferromagnetic layer and those of the ferromagnetic layer arediscontinuous in at least part of the interface thereof as observed inthe cross section cut parallel to the layer thickness, the crystal planeof the antiferromagnetic layer preferentially aligned parallel to thelayer surface may be different from the crystal plane of theferromagnetic layer preferentially aligned parallel to the layersurface. In this case also, a proper order transformation occurs in theantiferromagnetic layer through heat treatment and an increased exchangecoupling magnetic field can be generated.

EXAMPLE

[0375] A spin-valve film having the layer configurations described belowwas made. The content of Pt contained in a PtMn alloy layer constitutingan antiferromagnetic layer is changed so as to examine the relationshipbetween the Pt content and the exchange coupling magnetic field (Hex).

[0376] The spin-valve film included, from the bottom: a Si substrate; analumina layer; a Ta underlayer 3 nm in thickness; a NiFe seed layer 3 nmin thickness; a Pt_(x)Mn_(100−x) antiferromagnetic layer 15 nm inthickness; a pinned magnetic layer composed of a Co layer 1.5 nm inthickness, a Ru layer 0.8 nm in thickness, and a Co layer 2.5 nm inthickness; a Cu nonmagnetic interlayer 2.3 nm in thickness; a freemagnetic layer composed of a Co layer 1 nm in thickness and a NiFe layer3 nm in thickness; a Cu back layer 1.5 nm in thickness; and a Taprotective layer 3 nm in thickness.

[0377] Subsequent to the deposition of the layers of the spin-valvefilm, the deposited layers were heat-treated at a temperature of 200° C.or more for 2 hours of more. The exchange coupling magnetic field wasthen measured. The results are shown in FIG. 13.

[0378] As shown in FIG. 13, the exchange coupling magnetic field (Hex)increased as the Pt content X was increased to approximately 50 to 55atomic percent. When the Pt content exceeded approximately 55 atomicpercent, the exchange coupling magnetic field was gradually decreased.

[0379] In this invention, a preferable Pt content was defined as thecontent generating an exchange coupling magnetic field of 1.58×10⁴ (A/m)or more. From the results shown in FIG. 13, the preferable range of Ptcontent was determined to be between 45 atomic percent and 60 atomicpercent.

[0380] In this invention, a further preferable Pt content was defined asthe content generating an exchange coupling magnetic field of 7.9×10⁴(A/m) or more. From the results shown in FIG. 13, the further preferablerange of Pt content was determined to be between 49 atomic percent and56.5 atomic percent.

[0381] The intensity of the exchange coupling magnetic field changes inrelation with the Pt content since the conditions in the interfacesbetween the antiferromagnetic layer and the ferromagnetic layer (pinnedmagnetic layer) are changed by changing the Pt content.

[0382] The lattice constant of the antiferromagnetic layer is increasedas the Pt content is increased. In this respect, by increasing theamount of Pt, the difference in lattice constant between theantiferromagnetic layer and the ferromagnetic layer can be increased,and the interface between the antiferromagnetic layer and theferromagnetic layer can more readily enter a lattice-mismatching state.

[0383] Meanwhile, by providing a seed layer under the antiferromagneticlayer as above, the {111} planes in the each of the layers deposited onthe seed layer, namely the {111} planes in the antiferromagnetic layer,can be more easily preferentially aligned parallel to the layer surface.

[0384] The amount of Pt should not be excessive. When the Pt content isexcessive, a proper order transformation cannot be achieved in theantiferromagnetic layer even when the heat treatment is performed.

[0385] In this invention, the antiferromagnetic layer after the heattreatment achieves a proper order transformation while maintaining thelattice-mismatching state in the interface with the antiferromagneticlayer as a result of providing the seed layer under theantiferromagnetic layer and optimizing the Pt content in theantiferromagnetic layer. After the heat treatment, the crystal planes ofthe antiferromagnetic layer and the ferromagnetic layer preferentiallyaligned parallel to the layer surface are crystallographically identicaland the crystallographically identical axes lying in these crystalplanes are oriented, at least partly, in different directions betweenthe antiferromagnetic layer and the ferromagnetic layer.

[0386] When a cross-section of the antiferromagnetic layer and theferromagnetic layer parallel to the layer thickness is examined, thecrystal boundaries of the antiferromagnetic layer and the crystalboundaries of the ferromagnetic layer are, at least partly,discontinuous at the interface between the antiferromagnetic layer andthe ferromagnetic layer.

[0387] As is apparent from the detailed description above, in theexchange coupling film of the present invention, the crystal planesaligned parallel to the interface between the antiferromagnetic layerand the ferromagnetic layer are crystallographically identical.Moreover, the crystal axes lying in these planes are oriented, at leastpartly, in different directions between the antiferromagnetic layer andthe ferromagnetic layer.

[0388] In the present invention, the seed layer is preferably providedunder the antiferromagnetic layer. In this manner, it becomes easy topreferentially align the same crystal plane parallel to the layersurface in each of the antiferromagnetic layer and ferromagnetic layerformed above the seed layer. When the same crystal plane ispreferentially aligned in each of the antiferromagnetic layer and theferromagnetic layer, the rate of change in resistance can be increased.

[0389] The exchange coupling film of the present invention can beincorporated in various types of magnetoresistive elements. Amagnetoresistive element comprising the exchange coupling film iscapable of meeting the trends toward higher recording density.

What is claimed is:
 1. An exchange coupling film comprising anantiferromagnetic layer and a ferromagnetic layer in contact with theantiferromagnetic layer, an exchange coupling magnetic field generatedat the interface between the antiferromagnetic layer and theferromagnetic layer magnetizing the antiferromagnetic layer in aparticular direction, wherein the antiferromagnetic layer comprises anantiferromagnetic material containing Mn and X, wherein X is at leastone element selected from the group consisting Pt, Pd, Ir, Rh, Ru, andOs, and wherein crystal planes of the antiferromagnetic layer and theferromagnetic layer preferentially aligned parallel to the interface arecrystallographically identical, and crystallographically identical axeslying in said crystal planes are oriented, at least partly, in differentdirections between the antiferromagnetic layer and the ferromagneticlayer.
 2. An exchange coupling film according to claim 1, wherein thecrystal planes are the crystallographically identical planes genericallydescribed as the {111} planes.
 3. An exchange coupling film according toclaim 2, wherein the crystallographically identical axes are the axesgenerically described as the <110> axes.
 4. An exchange coupling filmaccording to claim 1, wherein the antiferromagnetic layer and theferromagnetic layer are deposited in that order from the bottom, theexchange coupling film further comprising a seed layer provided belowthe antiferromagnetic layer, the seed layer mainly having aface-centered cubic structure and having one of the crystallographicallyidentical planes generically described as the {111} planespreferentially aligned parallel to the interface.
 5. An exchangecoupling film according to claim 4, wherein the seed layer comprises oneof a NiFe alloy and a Ni—Fe—Y alloy, wherein Y is at least one elementselected from the group consisting of Cr, Rh, Ta, Hf, Nb, Zr, and Ti. 6.An exchange coupling film according to claim 4, wherein the seed layeris nonmagnetic at room temperature.
 7. An exchange coupling filmaccording to claim 4, further comprising an underlayer provided underthe seed layer, the underlayer comprising at least one element selectedfrom the group consisting of Ta, Hf, Nb, Zr, Ti, Mo, and W.
 8. Anexchange coupling film according to claim 4, wherein at least part ofthe interface between the antiferromagnetic layer and the seed layer isin a lattice-mismatching state.
 9. An exchange coupling film accordingto claim 1, the antiferromagnetic material further comprising X′,wherein X′ is at least one element selected from the group consisting ofNe, Ar, Kr, Xe, Be, B, C, N, Mg, Al, Si, P, Ti, V, Cr, Fe, Co, Ni, Cu,Zn, Ga, Ge, Zr, Nb, Mo, Ag, Cd, Sn, Hf, Ta, W, Re, Au, Pb, and rareearth elements.
 10. An exchange coupling film according to claim 9,wherein the antiferromagnetic material is an interstitial solid solutionin which said X′ is inserted to interstices in the lattice formed by Xand Mn or a substitutional solid solution in which said X′ partlydisplaces the lattice points in the crystal lattice formed by X and Mn.11. An exchange coupling film according to claim 10, wherein the X orX+X′ content in the antiferromagnetic material is in the range of 45 to60 atomic percent.
 12. An exchange coupling film according to claim 1,wherein at least part of the interface between the antiferromagneticlayer and the ferromagnetic layer is in a lattice-mismatching state. 13.A magnetoresistive element comprising: an exchange coupling filmaccording to claim 1; a free magnetic layer formed on the pinnedmagnetic layer separated by a nonmagnetic interlayer; and bias layersfor magnetizing the free magnetic layer in a direction substantiallyorthogonal to the magnetization vector of the pinned magnetic layer. 14.A magnetoresistive element comprising: an antiferromagnetic layer; apinned magnetic layer in contact with the antiferromagnetic layer, themagnetization vectors of the pinned magnetic layer being pinned by anexchange anisotropic magnetic field generated in relation to theantiferromagnetic layer; a free magnetic layer formed on the pinnedmagnetic layer separated by a nonmagnetic interlayer; andantiferromagnetic exchange bias layers formed above or below the freemagnetic layer, the exchange bias layers being separated from oneanother in a track width direction by a gap therebetween, wherein theexchange bias layers and the free magnetic layer comprise an exchangecoupling film according to claim 1, the exchange bias layerscorresponding to the antiferromagnetic layer and the free magnetic layercorresponding to the ferromagnetic layer, so as to magnetize the freemagnetic layer in a particular direction.
 15. A magnetoresistive elementcomprising: nonmagnetic interlayers provided above and below a freemagnetic layer; pinned magnetic layers, one thereof being provided onthe pinned magnetic layer formed on the free magnetic layer and theother being provided under the pinned magnetic layer formed under thefree magnetic layer; antiferromagnetic layers for pinning themagnetization vectors of the pinned magnetic layers, one of theantiferromagnetic layers being provided on one of the pinned magneticlayers and the other being provided under the other of the pinnedmagnetic layers; and bias layers for orienting the magnetization vectorof the free magnetic layer in a direction substantially orthogonal tothe magnetization vector of the pinned magnetic layer, wherein eachantiferromagnetic layer and the pinned magnetic layer in contact withthe antiferromagnetic layer comprise an exchange coupling film accordingto claim 1, the pinned magnetic layer corresponding to the ferromagneticlayer.
 16. A magnetoresistive element comprising: a magnetoresistivelayer; a soft magnetic layer provided on the magnetoresistive layerseparated by a nonmagnetic layer therebetween; and antiferromagneticlayers provided above or below the magnetoresistive layer, theantiferromagnetic layers being separated from one another in a trackwidth direction with a gap therebetween, wherein the antiferromagneticlayers and the magnetoresistive layer comprise an exchange coupling filmaccording to claim 1, the magnetoresistive layer corresponding to theferromagnetic layer.
 17. An exchange coupling film comprising anantiferromagnetic layer and a ferromagnetic layer in contact with theantiferromagnetic layer, in which an exchange coupling magnetic fieldgenerated at the interface between the antiferromagnetic layer and theferromagnetic layer magnetizes the ferromagnetic layer in a particulardirection, wherein diffraction spots corresponding to reciprocal latticepoints indicative of crystal planes of the antiferromagnetic layer andthe ferromagnetic layer appear in transmission electron beam diffractiondiagrams of the antiferromagnetic layer and the ferromagnetic layerobtained using an electron beam in a direction parallel to theinterface, wherein first imaginary lines in the diffraction diagrams ofthe antiferromagnetic layer and the ferromagnetic layer, the firstimaginary lines each connecting a beam origin and a particular one ofthe diffraction spots which is given the same label in both thediffraction diagrams of the antiferromagnetic layer and theferromagnetic layer and which is located in a layer thickness directionwhen viewed from the beam origin, are coincident with each other, andwherein second imaginary line in the diffraction diagrams of theantiferromagnetic layer and the ferromagnetic layer, the secondimaginary lines each connecting the beam origin and a particular one ofthe diffraction spots which is given the same label in both thediffraction diagrams of the antiferromagnetic layer and theferromagnetic layer and which is located in a direction other than thelayer thickness direction when viewed from the beam origin, are notcoincident with each other.
 18. An exchange coupling film according toclaim 17, wherein the diffraction spots located in the layer thicknessdirection are assigned to the {111} planes.
 19. An exchange couplingfilm according to claim 17, wherein the antiferromagnetic layer and theferromagnetic layer are deposited in that order from the bottom, theexchange coupling film further comprising a seed layer provided belowthe antiferromagnetic layer, the seed layer mainly having aface-centered cubic structure and having the crystallographicallyidentical planes generically described as the {111} planes, one of the{111} planes being preferentially aligned parallel to the interface. 20.An exchange coupling film according to claim 19, wherein the seed layercomprises one of a NiFe alloy and a Ni—Fe—Y alloy, wherein Y is at leastone element selected from the group consisting of Cr, Rh, Ta, Hf, Nb,Zr, and Ti.
 21. An exchange coupling film according to claim 19, whereinthe seed layer is nonmagnetic at room temperature.
 22. An exchangecoupling film according to claim 19, further comprising an underlayerprovided under the seed layer, the underlayer comprising at least oneelement selected from the group consisting of Ta, Hf, Nb, Zr, Ti, Mo,and W.
 23. An exchange coupling film according to claim 19, wherein atleast part of the interface between the antiferromagnetic layer and theseed layer is in a lattice-mismatching state.
 24. An exchange couplingfilm according to claim 19, the antiferromagnetic material furthercomprising X′, wherein X′ is at least one element selected from thegroup consisting of Ne, Ar, Kr, Xe, Be, B, C, N, Mg, Al, Si, P, Ti, V,Cr, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo, Ag, Cd, Sn, Hf, Ta, W, Re,Au, Pb, and rare earth elements.
 25. An exchange coupling film accordingto claim 24, wherein the antiferromagnetic material is an interstitialsolid solution in which X′ is inserted to interstices in the latticeformed by X and Mn or a substitutional solid solution in which X′ partlydisplaces the lattice points in the crystal lattice formed by X and Mn.26. An exchange coupling film according to claim 25, wherein the X orX+X′ content in the antiferromagnetic material is in the range of 45 to60 atomic percent.
 27. An exchange coupling film according to claim 17,wherein at least part of the interface between the antiferromagneticlayer and the ferromagnetic layer is in a lattice-mismatching state. 28.A magnetoresistive element comprising: an antiferromagnetic layer; apinned magnetic layer in contact with the antiferromagnetic layer, themagnetization vector of the pinned magnetic layer being pinned by anexchanged anisotropic magnetic field generated in relation to theantiferromagnetic layer; a free magnetic layer formed on the pinnedmagnetic layer separated by a nonmagnetic interlayer therebetween; andbias layers for orienting the magnetization vector of the free magneticlayer in a direction substantially orthogonal to the magnetizationvector of the pinned magnetic layer, wherein the antiferromagnetic layerand the pinned magnetic layer comprise an exchange coupling filmaccording to claim 17, the pinned magnetic layer corresponding to theferromagnetic layer.
 29. A magnetoresistive element comprising: anantiferromagnetic layer; a pinned magnetic layer in contact with theantiferromagnetic layer, the magnetization vectors of the pinnedmagnetic layer being pinned by an exchange anisotropic magnetic fieldgenerated in relation with the antiferromagnetic layer; a free magneticlayer formed on the pinned magnetic layer separated by a nonmagneticinterlayer; and antiferromagnetic exchange bias layers formed above orunder the free magnetic layer, the exchange bias layers being separatedfrom one another in a track width direction by a gap therebetween,wherein the exchange bias layers and the free magnetic layer comprise anexchange coupling film according to claim 17, the exchange bias layerscorresponding to the antiferromagnetic layer and the free magnetic layercorresponding to the ferromagnetic layer.
 30. A magnetoresistive elementcomprising: nonmagnetic interlayers provided above and below a freemagnetic layer; pinned magnetic layers, one thereof being provided onthe pinned magnetic layer formed on the free magnetic layer and theother being provided under the pinned magnetic layer formed under thefree magnetic layer; antiferromagnetic layers for pinning themagnetization vectors of the pinned magnetic layers, one of theantiferromagnetic layers being provided on one of the pinned magneticlayers and the other being provided under the other of the pinnedmagnetic layers; and bias layers for orienting the magnetization vectorof the free magnetic layer in a direction substantially orthogonal tothe magnetization vector of the pinned magnetic layer, wherein theantiferromagnetic layer and the-pinned magnetic layer in contact withthe antiferromagnetic layer comprise an exchange coupling film accordingto claim 17, the pinned magnetic layer corresponding to theferromagnetic layer.
 31. A magnetoresistive element comprising: amagnetoresistive layer; a soft magnetic layer provided on themagnetoresistive layer separated by a nonmagnetic layer therebetween;and antiferromagnetic layers provided above or below themagnetoresistive layer, the antiferromagnetic layers being separatedfrom one another in a track width direction with a gap therebetween,wherein the antiferromagnetic layer and the magnetoresistive layercomprise an exchange coupling film according to claim 17, themagnetoresistive layer corresponding to the ferromagnetic layer.
 32. Anexchange coupling film comprising an antiferromagnetic layer and aferromagnetic layer in contact with the antiferromagnetic layer, inwhich an exchange coupling magnetic field generated at the interfacebetween the antiferromagnetic layer and the ferromagnetic layer orientsthe magnetization vector of the ferromagnetic layer in a particulardirection, wherein diffraction spots corresponding to reciprocal latticepoints indicative of crystal planes of the antiferromagnetic layer andthe ferromagnetic layer appear in transmission electron beam diffractiondiagrams of the antiferromagnetic layer and the ferromagnetic layerobtained using an electron beam in a direction parallel to theinterface, wherein first imaginary lines in the diffraction diagrams ofthe antiferromagnetic layer and the ferromagnetic layer, the firstimaginary lines each connecting a beam origin and a particular one ofthe diffraction spots which is given the same label in both thediffraction diagrams of the antiferromagnetic layer and theferromagnetic layer and is located in a layer thickness direction whenviewed from the beam origin, are coincident with each other, and whereina particular diffraction spot indicative of a particular crystal plane,located in a direction other than the layer thickness direction, appearsonly in one of the diffraction diagrams of the antiferromagnetic layerand the ferromagnetic layer.
 33. An exchange coupling film according toclaim 32, wherein the diffraction spots located in the layer thicknessdirection are assigned to the {111} planes.
 34. An exchange couplingfilm according to claim 32, wherein the antiferromagnetic layer and theferromagnetic layer are deposited in that order from the bottom, theexchange coupling film further comprising a seed layer provided belowthe antiferromagnetic layer, the seed layer mainly having aface-centered cubic structure and having the crystallographicallyidentical planes generically described as the {111} planes, one of whichis preferentially aligned parallel to the interface.
 35. An exchangecoupling film according to claim 34, the seed layer comprising one of aNiFe alloy and a Ni—Fe—Y alloy, wherein Y is at least one elementselected from the group consisting of Cr, Rh, Ta, Hf, Nb, Zr, and Ti.36. An exchange coupling film according to claim 34, wherein the seedlayer is nonmagnetic at room temperature.
 37. An exchange coupling filmaccording to claim 34, further comprising an underlayer provided underthe seed layer, the underlayer comprising at least one element selectedfrom the group consisting of Ta, Hf, Nb, Zr, Ti, Mo, and W.
 38. Anexchange coupling film according to claim 34, wherein at least part ofthe interface between the antiferromagnetic layer and the seed layer isin a lattice-mismatching state.
 39. An exchange coupling film accordingto claim 32, the antiferromagnetic material further comprising X′,wherein X′ is at least one element selected from the group consisting ofNe, Ar, Kr, Xe, Be, B, C, N, Mg, Al, Si, P, Ti, V, Cr, Fe, Co, Ni, Cu,Zn, Ga, Ge, Zr, Nb, Mo, Ag, Cd, Sn, Hf, Ta, W, Re, Au, Pb, and rareearth elements.
 40. An exchange coupling film according to claim 39,wherein the antiferromagnetic material is an interstitial solid solutionin which X′ is inserted to interstices in the lattice formed by X and Mnor a substitutional solid solution in which X′ partly displaces thelattice points in the crystal lattice formed by X and Mn.
 41. Anexchange coupling film according to claim 40, wherein the X or X+X′content in the antiferromagnetic material is in the range of 45 to 60atomic percent.
 42. An exchange coupling film according to claim 32,wherein at least part of the interface between the antiferromagneticlayer and the ferromagnetic layer is in a lattice-mismatching state. 43.A magnetoresistive element comprising: an antiferromagnetic layer; apinned magnetic layer in contact with the antiferromagnetic layer, themagnetization vector of the pinned magnetic layer being pinned by anexchanged anisotropic magnetic field generated in relation to theantiferromagnetic layer; a free magnetic layer formed on the pinnedmagnetic layer separated by a nonmagnetic interlayer therebetween; andbias layers for orienting the magnetization vector of the free magneticlayer in a direction substantially orthogonal to the magnetizationvector of the pinned magnetic layer, wherein the antiferromagnetic layerand the pinned magnetic layer comprises an exchange coupling filmaccording to claim 32, the pinned magnetic layer corresponding to theferromagnetic layer.
 44. A magnetoresistive element comprising: anantiferromagnetic layer; a pinned magnetic layer in contact with theantiferromagnetic layer, the magnetization vectors of the pinnedmagnetic layer being pinned by an exchange anisotropic magnetic fieldgenerated in relation to the antiferromagnetic layer; a free magneticlayer formed on the pinned magnetic layer separated by a nonmagneticinterlayer; and antiferromagnetic exchange bias layers formed above orunder the free magnetic layer, the exchange bias layers being separatedfrom one another in a track width direction by a gap therebetween,wherein the exchange bias layers and the free magnetic layer comprise anexchange coupling film according to claim 32, the exchange bias layerscorresponding to the antiferromagnetic material and the free magneticlayer corresponding to the ferromagnetic layer.
 45. A magnetoresistiveelement comprising: nonmagnetic interlayers provided above and below afree magnetic layer; pinned magnetic layers, one thereof being providedon the pinned magnetic layer formed on the free magnetic layer and theother being provided under the pinned magnetic layer formed under thefree magnetic layer; antiferromagnetic layers for pinning themagnetization vectors of the pinned magnetic layers, one of theantiferromagnetic layers being provided on one of the pinned magneticlayers and the other being provided under the other of the pinnedmagnetic layers; and bias layers for orienting the magnetization vectorof the free magnetic layer in a direction substantially orthogonal tothe magnetization vector of the pinned magnetic layer, wherein theantiferromagnetic layer and the pinned magnetic layer in contact withthe antiferromagnetic layer comprise an exchange coupling film accordingto claim 32, the pinned magnetic layer corresponding to theferromagnetic layer.
 46. A magnetoresistive element comprising: amagnetoresistive layer; a soft magnetic layer provided on themagnetoresistive layer separated by a nonmagnetic layer therebetween;and antiferromagnetic layers provided above or below themagnetoresistive layer, the antiferromagnetic layers being separatedfrom one another in a track width direction with a gap therebetween,wherein the antiferromagnetic layer and the magnetoresistive layercomprise an exchange coupling film according to claim 32, themagnetoresistive layer corresponding to the ferromagnetic layer.
 47. Anexchange coupling film comprising an antiferromagnetic layer and aferromagnetic layer in contact with the antiferromagnetic layer, anexchange coupling magnetic field generated at the interface between theantiferromagnetic layer and the ferromagnetic layer magnetizing theferromagnetic layer in a particular direction, wherein diffraction spotscorresponding to reciprocal lattice points indicative of crystal planesof the antiferromagnetic layer and the ferromagnetic layer appear intransmission electron beam diffraction diagrams of the antiferromagneticlayer and the ferromagnetic layer obtained using an electron beam in adirection perpendicular to the interface, and wherein an imaginary linein the diffraction diagram of the antiferromagnetic layer connecting abeam origin and a diffraction spot given a particular label and animaginary line in the diffraction diagram of the ferromagnetic layerconnecting the beam origin and a diffraction spot given the same labelare not coincident with each other.
 48. An exchange coupling filmaccording to claim 47, wherein the direction perpendicular to theinterface is the direction of the crystallographically identical crystalaxes generically described as the <111> axes.
 49. An exchange couplingfilm according to claim 47, wherein the antiferromagnetic layer and theferromagnetic layer have the crystallographically identical planesgenerically described as the {111} planes, one of which ispreferentially aligned parallel to the interface between theantiferromagnetic layer and the ferromagnetic layer.
 50. An exchangecoupling film according to claim 47, wherein the antiferromagnetic layerand the ferromagnetic layer are deposited in that order from the bottom,the exchange coupling film further comprising a seed layer providedbelow the antiferromagnetic layer, the seed layer mainly having aface-centered cubic structure and having crystallographically identicalplanes generically described as the {111} planes, one of which ispreferentially aligned parallel to the interface.
 51. An exchangecoupling film according to claim 50, the seed layer comprising one of aNiFe alloy and a Ni—Fe—Y alloy, wherein Y is at least one elementselected from the group consisting of Cr, Rh, Ta, Hf, Nb, Zr, and Ti.52. An exchange coupling film according to claim 50, wherein the seedlayer is nonmagnetic at room temperature.
 53. An exchange coupling filmaccording to claim 50, further comprising an underlayer provided underthe seed layer, the underlayer comprising at least one element selectedfrom the group consisting of Ta, Hf, Nb, Zr, Ti, Mo, and W.
 54. Anexchange coupling film according to claim 50, wherein at least part ofthe interface between the antiferromagnetic layer and the seed layer isin a lattice-mismatching state.
 55. An exchange coupling film accordingto claim 47, the antiferromagnetic material further comprising X′,wherein X′ is at least one element selected from the group consisting ofNe, Ar, Kr, Xe, Be, B, C, N, Mg, Al, Si, P, Ti, V, Cr, Fe, Co, Ni, Cu,Zn, Ga, Ge, Zr, Nb, Mo, Ag, Cd, Sn, Hf, Ta, W, Re, Au, Pb, and rareearth elements.
 56. An exchange coupling film according to claim 55,wherein the antiferromagnetic material is an interstitial solid solutionin which X′ is inserted to interstices in the lattice formed by X and Mnor a substitutional solid solution in which X′ partly displaces latticepoints in the crystal lattice formed by X and Mn.
 57. An exchangecoupling film according to claim 56, wherein the X or X+X′ content inthe antiferromagnetic material is in the range of 45 to 60 atomicpercent.
 58. An exchange coupling film according to claim 47, wherein atleast part of the interface between the antiferromagnetic layer and theferromagnetic layer is in a lattice-mismatching state.
 59. Amagnetoresistive element comprising: an antiferromagnetic layer; apinned magnetic layer in contact with the antiferromagnetic layer, themagnetization vector of the pinned magnetic layer being pinned by anexchanged anisotropic magnetic field generated in relation to theantiferromagnetic layer; a free magnetic layer formed on the pinnedmagnetic layer separated by a nonmagnetic interlayer therebetween; andbias layers for orienting the magnetization vector of the free magneticlayer in a direction substantially orthogonal to the magnetizationvector of the pinned magnetic layer, wherein the antiferromagnetic layerand the pinned magnetic layer comprises an exchange coupling filmaccording to claim 47, the pinned magnetic layer corresponding to theferromagnetic layer.
 60. A magnetoresistive element comprising: anantiferromagnetic layer; a pinned magnetic layer in contact with theantiferromagnetic layer, the magnetization vectors of the pinnedmagnetic layer being pinned by an exchange anisotropic magnetic fieldgenerated in relation with the antiferromagnetic layer; a free magneticlayer formed on the pinned magnetic layer separated by a nonmagneticinterlayer; and antiferromagnetic exchange bias layers formed above orbelow the free magnetic layer, the exchange bias layers being separatedfrom one another in a track width direction by a gap therebetween,wherein the exchange bias layers and the free magnetic layer comprise anexchange coupling film according to claim 47, the exchange bias layerscorresponding to the antiferromagnetic layer and the free magnetic layercorresponding to the ferromagnetic layer.
 61. A magnetoresistive elementcomprising: nonmagnetic interlayers provided below and above a freemagnetic layer; pinned-magnetic layers, one thereof being provided onthe pinned magnetic layer formed on the free magnetic layer and theother being provided under the pinned magnetic layer formed under thefree magnetic layer; antiferromagnetic layers for pinning themagnetization vectors of the pinned magnetic layers, one of theantiferromagnetic layers being provided on one of the pinned magneticlayers and the other being provided under the other of the pinnedmagnetic layers; and bias layers for orienting the magnetization vectorof the free magnetic layer in a direction substantially orthogonal tothe magnetization vector of the pinned magnetic layer, wherein theantiferromagnetic layer and the pinned magnetic layer in contact withthe antiferromagnetic layer comprise an exchange coupling film accordingto claim 47, the pinned magnetic layer corresponding to theferromagnetic layer.
 62. A magnetoresistive element comprising: amagnetoresistive layer; a soft magnetic layer provided on themagnetoresistive layer separated by a nonmagnetic layer therebetween;and antiferromagnetic layers provided above or below themagnetoresistive layer, the antiferromagnetic layers being separatedfrom one another in a track width direction with a gap therebetween,wherein the antiferromagnetic layer and the magnetoresistive layercomprise an exchange coupling film according to claim 47, themagnetoresistive layer corresponding to the ferromagnetic layer.
 63. Anexchange coupling film comprising an antiferromagnetic film and aferromagnetic film in contact with the antiferromagnetic layer, anexchange coupling magnetic field generated at the interface between theantiferromagnetic layer and the ferromagnetic layer magnetizing theferromagnetic layer in a particular direction, wherein diffraction spotscorresponding to reciprocal lattice points indicative of crystal planesof the antiferromagnetic layer and the ferromagnetic layer appear intransmission electron beam diffraction diagrams of the antiferromagneticlayer and the ferromagnetic layer obtained using an electron beam in adirection perpendicular to the interface, and wherein, among saiddiffraction spots, a diffraction spot given a particular label appearsonly in one of the diffraction diagrams of the antiferromagnetic layerand the ferromagnetic layer.
 64. An exchange coupling film according toclaim 63, wherein the direction perpendicular to the interface is thedirection of the crystallographically identical crystal axes genericallydescribed as the <111> axes.
 65. An exchange coupling film according toclaim 63, wherein the antiferromagnetic layer and the ferromagneticlayer have the crystallographically identical planes genericallydescribed as the {111} planes, one of which is preferentially alignedparallel to the interface between the antiferromagnetic layer and theferromagnetic layer.
 66. An exchange coupling film according to claim63, wherein the antiferromagnetic layer and the ferromagnetic layer aredeposited in that order from the bottom, the exchange coupling filmfurther comprising a seed layer provided below the antiferromagneticlayer, the seed layer mainly having a face-centered cubic structure andhaving the crystallographically identical planes generically describedas the {111} planes, one of which is preferentially aligned parallel tothe interface.
 67. An exchange coupling film according to claim 66, theseed layer comprising one of a NiFe alloy and a Ni—Fe—Y alloy, wherein Yis at least one element selected from the group consisting of Cr, Rh,Ta, Hf, Nb, Zr, and Ti.
 68. An exchange coupling film according to claim66, wherein the seed layer is nonmagnetic at room temperature.
 69. Anexchange coupling film according to claim 66, further comprising anunderlayer provided under the seed layer, the underlayer comprising atleast one element selected from the group consisting of Ta, Hf, Nb, Zr,Ti, Mo, and W.
 70. An exchange coupling film according to claim 66,wherein at least part of the interface between the antiferromagneticlayer and the seed layer is in a lattice-mismatching state.
 71. Anexchange coupling film according to claim 63, wherein theantiferromagnetic material further comprises X′, wherein X′ is at leastone element selected from the group consisting of Ne, Ar, Kr, Xe, Be, B,C, N, Mg, Al, Si, P, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Ga, Ge, Zr, Nb, Mo,Ag, Cd, Sn, Hf, Ta, W, Re, Au, Pb, and rare earth elements.
 72. Anexchange coupling film according to claim 71, wherein theantiferromagnetic material is an interstitial solid solution in which X′is inserted to interstices in the lattice formed by X and Mn or asubstitutional solid solution in which X′ displaces part of the latticepoints in the crystal lattice formed by X and Mn.
 73. An exchangecoupling film according to claim 72, wherein the X or X+X′ content inthe antiferromagnetic material is in the range of 45 to 60 atomicpercent.
 74. An exchange coupling film according to claim 63, wherein atleast part of the interface between the antiferromagnetic layer and theferromagnetic layer is in a lattice-mismatching state.
 75. Amagnetoresistive element comprising: an antiferromagnetic layer; apinned magnetic layer in contact with the antiferromagnetic layer, themagnetization vector of the pinned magnetic layer being pinned by anexchanged anisotropic magnetic field generated in relation to theantiferromagnetic layer; a free magnetic layer formed on the pinnedmagnetic layer separated by a nonmagnetic interlayer therebetween; andbias layers for orienting the magnetization vector of the free magneticlayer in a direction substantially orthogonal to the magnetizationvector of the pinned magnetic layer, wherein the antiferromagnetic layerand the pinned magnetic layer comprises an exchange coupling filmaccording to claim 63, the pinned magnetic layer corresponding to theferromagnetic layer.
 76. A magnetoresistive element comprising: anantiferromagnetic layer; a pinned magnetic layer in contact with theantiferromagnetic layer, the magnetization vectors of the pinnedmagnetic layer being pinned by an exchange anisotropic magnetic fieldgenerated in relation to the antiferromagnetic layer; a free magneticlayer formed on the pinned magnetic layer separated by a nonmagneticinterlayer; and antiferromagnetic exchange bias layers formed above orunder the free magnetic layer, the exchange bias layers being separatedfrom one another in a track width direction by a gap therebetween,wherein the exchange bias layers and the free magnetic layer comprise anexchange coupling film according to claim 63, the exchange bias layerscorresponding to the antiferromagnetic layer and the free magnetic layercorresponding to the ferromagnetic layer.
 77. A magnetoresistive elementcomprising: nonmagnetic interlayers provided under and above a freemagnetic layer; pinned magnetic layers, one thereof being provided onthe pinned magnetic layer formed on the free magnetic layer and theother being provided under the pinned magnetic layer formed under thefree magnetic layer; antiferromagnetic layers for pinning themagnetization vectors of the pinned magnetic layers, one of theantiferromagnetic layers being provided on one of the pinned magneticlayers and the other being provided under the other of the pinnedmagnetic layers; and bias layers for orienting the magnetization vectorof the free magnetic layer in a direction substantially orthogonal tothe magnetization vector of the pinned magnetic layer, wherein theantiferromagnetic layer and the pinned magnetic layer in contact withthe antiferromagnetic layer comprise an exchange coupling film accordingto claim 63, the pinned magnetic layer corresponding to theferromagnetic layer.
 78. A magnetoresistive element comprising: amagnetoresistive layer; a soft magnetic layer provided on themagnetoresistive layer separated by a nonmagnetic layer therebetween;and antiferromagnetic layers provided above or below themagnetoresistive layer, the antiferromagnetic layers being separatedfrom one another in a track width direction with a gap therebetween,wherein the antiferromagnetic layer and the magnetoresistive layercomprise an exchange coupling film according to claim 63, themagnetoresistive layer corresponding to the ferromagnetic layer.